as shown in fig1 and 2 , a solid polymer electrolyte fuel cell 12 including a membrane electrode assembly 10 according to a first embodiment of the present invention is formed by sandwiching the membrane electrode assembly 10 between a first separator 14 and a second separator 16 . for example , the first separator 14 and the second separator 16 are made of metal plates such as steel plates , stainless steel plates , aluminum plates , plated steel sheets , or metal plates having anti - corrosive surfaces by surface treatment . alternatively , carbon members may be used as the first separator 14 and the second separator 16 . as shown in fig2 , the membrane electrode assembly 10 includes a solid polymer electrolyte membrane 18 , and an anode ( second electrode ) 20 and a cathode ( first electrode ) 22 sandwiching the solid polymer electrolyte membrane 18 . the solid polymer electrolyte membrane 18 is formed by impregnating a thin membrane of perfluorosulfonic acid with water , for example . a fluorine based electrolyte may be used as the solid polymer electrolyte membrane 18 . alternatively , an hc ( hydrocarbon ) based electrolyte may be used as the solid polymer electrolyte membrane 18 . the surface size ( surface area ) of the cathode 22 is smaller than the surface sizes ( surface areas ) of the solid polymer electrolyte membrane 18 and the anode 20 . it should be noted that the surface size of the cathode 22 may be equal to or larger than the surface size of the anode 20 . the anode 20 is provided on one surface 18 a of the solid polymer electrolyte membrane 18 and the cathode 22 is provided on the other surface 18 b of the solid polymer electrolyte membrane 18 such that a frame shaped outer portion of the solid polymer electrolyte membrane 18 is exposed . the anode 20 includes an electrode catalyst layer 20 a joined to the surface 18 a of the solid polymer electrolyte membrane 18 and a gas diffusion layer 20 c stacked on the electrode catalyst layer 20 a through an intermediate layer ( underlying layer ) 20 b . the cathode 22 includes an electrode catalyst layer 22 a joined to the surface 18 b of the solid polymer electrolyte membrane 18 and a gas diffusion layer 22 c stacked on the electrode catalyst layer 22 a through an intermediate layer ( underlying layer ) 22 b . each of the electrode catalyst layers 20 a , 22 a is formed by carbon black supporting platinum particles as catalyst particles . as an ion conductive binder , polymer electrolyte is used . catalyst paste formed by mixing the catalyst particles uniformly in the solution of this polymer electrolyte is printed , applied ( coated ) or transferred on both surfaces 18 a , 18 b of the solid polymer electrolyte membrane 18 to form the electrode catalyst layers 20 a , 22 a . carbon black and fep ( fluorinated ethylene - propylene copolymer ) particles and carbon nanotube are prepared in a form of paste , and coated on the gas diffusion layer 20 c , 22 c to form the intermediate layers 20 b , 22 b . the gas diffusion layers 20 c , 22 c are made of carbon papers or the like , and the surface size of the gas diffusion layer 20 c is larger that the surface size of the gas diffusion layer 22 c . as shown in fig2 and 3 , the membrane electrode assembly 10 includes a resin frame member 24 formed around the solid polymer electrolyte membrane 18 , and joined only to the cathode 22 of the solid polymer electrolyte membrane 18 . for example , the resin frame member 24 is made of pps ( poly phenylene sulfide ), ppa ( polyphthalamide ), etc ., and includes an impregnation portion 26 for impregnation of only the outer marginal portion of the cathode 22 with the inner marginal portion of the resin frame member 24 . as shown in fig1 , at one end of the fuel cell 12 in a direction indicated by an arrow b ( horizontal direction in fig1 ), an oxygen - containing gas supply passage 30 a for supplying an oxygen - containing gas , a coolant supply passage 32 a for supplying a coolant , and a fuel gas discharge passage 34 b for discharging a fuel gas such as a hydrogen - containing gas are arranged in a vertical direction indicated by an arrow c . the oxygen - containing gas supply passage 30 a , the coolant supply passage 32 a , and the fuel gas discharge passage 34 b extend through the fuel cell 12 in a stacking direction indicated by an arrow a . at the other end of the fuel cell 12 in the direction indicated by the arrow b , a fuel gas supply passage 34 a for supplying the fuel gas , a coolant discharge passage 32 b for discharging the coolant , and an oxygen - containing gas discharge passage 30 b for discharging the oxygen - containing gas are arranged in the direction indicated by the arrow c . the fuel gas supply passage 34 a , the coolant discharge passage 32 b , and the oxygen - containing gas discharge passage 30 b extend through the fuel cell 12 in the direction indicated by the arrow a . the second separator 16 has an oxygen - containing gas flow field 36 on its surface 16 a facing the membrane electrode assembly 10 . the oxygen - containing gas flow field 36 is connected to the oxygen - containing gas supply passage 30 a and the oxygen - containing gas discharge passage 30 b . the first separator 14 has a fuel gas flow field 38 on its surface 14 a facing the membrane electrode assembly 10 . the fuel gas flow field 38 is connected to the fuel gas supply passage 34 a and the fuel gas discharge passage 34 b . a coolant flow field 40 is formed between a surface 14 b of the first separator 14 and a surface 16 b of the second separator 16 . the coolant flow field 40 is connected to the coolant supply passage 32 a and the coolant discharge passage 32 b . as shown in fig1 and 2 , a first seal member 42 is formed integrally with the surfaces 14 a , 14 b of the first separator 14 , around the outer end of the first separator 14 . a second seal member 44 is formed integrally with the surfaces 16 a , 16 b of the second separator 16 , around the outer end of the second separator 16 . as shown in fig2 , the first seal member 42 includes a first ridge seal 42 a which contacts the resin frame member 24 of the membrane electrode assembly 10 , and a second ridge seal 42 b interposed between the first separator 14 and the second separator 16 . the second seal member 44 is a flat surface seal . instead of providing the second ridge seal 42 b , the second seal member 44 may have a ridge seal ( not shown ). each of the first seal member 42 and the second seal members 44 is made of seal material , cushion material , or packing material such as an epdm ( ethylene propylene diene monomer ) rubber , an nbr ( nitrile butadiene rubber ), a fluoro rubber , a silicone rubber , a fluorosilicone rubber , a butyl rubber , a natural rubber , a styrene rubber , a chloroprene rubber , or an acrylic rubber . as shown in fig1 , the first separator 14 has supply holes 46 connecting the fuel gas supply passage 34 a to the fuel gas flow field 38 , and discharge holes 48 connecting the fuel gas flow field 38 to the fuel gas discharge passage 34 b . in this fuel cell 12 , a method of producing the membrane electrode assembly 10 according to a first embodiment of the present invention will be described below . firstly , as shown in fig4 , an mea 50 having different sizes of components is produced . specifically , the electrode catalyst layers 20 a , 22 a are coated on both surfaces 18 a , 18 b of the solid polymer electrolyte membrane 18 , and the intermediate layers 20 b , 22 b each comprising a mixture of water - repellent agent and carbon particles are coated on the gas diffusion layers 20 c , 22 c . then , the gas diffusion layer 20 c is placed on a side adjacent to the surface 18 a of the solid polymer electrolyte membrane 18 , i . e ., the gas diffusion layer 20 c is placed such that the intermediate layer 20 b faces the electrode catalyst layer 20 a . further , the gas diffusion layer 22 c is placed on a side adjacent to the surface 18 b of the solid polymer electrolyte membrane 18 , i . e ., the gas diffusion layer 22 c is placed such that the intermediate layer 22 b faces the electrode catalyst layer 22 a . these components are stacked together , and subjected to hot pressing treatment to produce the mea 50 . as shown in fig5 , the resin frame member 24 is formed by an injection molding machine ( not shown ) beforehand . the dimension ( width ) h 1 of the resin frame member 24 and the dimension ( thickness ) h 1 of the mea 50 are the same . the resin frame member 24 has an inner extension 24 a at its inner marginal portion . the thickness h 2 of the inner extension 24 a and the thickness h 2 of the cathode 22 of the mea 50 are the same . the extension length l of the inner extension 24 a is the sum of the distance from the front end of the solid polymer electrolyte membrane 18 of the mea 50 to the front end of the cathode 22 and the length of the impregnation portion 26 . next , as shown in fig6 , the mea 50 is placed on a base table 52 such that the anode 20 is positioned on the lower side . the front end of the inner extension 24 a of the resin frame member 24 is overlapped with the outer marginal portion of the cathode 22 of the mea 50 . a glass plate 54 is placed on the resin frame member 24 . a load f is applied to the resin frame member 24 through the glass plate 54 , toward the base table 52 , and a laser beam lb is radiated from a laser machine 56 through the glass plate 54 to the overlapped portions ( an area where the outer marginal portion of the cathode 22 and the inner marginal portion of the resin frame member 24 are overlapped with each other ). thus , the inner extension 24 a of the resin frame member 24 as the inner marginal portion is locally heated in a concentrated manner , and melted . the gas diffusion layer 22 c of the cathode 22 is impregnated with the melted resin of the inner extension 24 a of the resin frame member 24 . therefore , as shown in fig2 , the resin frame member 24 is joined to the cathode 22 by the impregnation portion 26 where only the outer marginal portion of the cathode 22 is impregnated with the melted resin of the inner marginal portion of the resin frame member 24 . in this manner , the membrane electrode assembly 10 is produced . in the first embodiment , after the mea 50 and the resin frame member 24 are produced separately , only the outer marginal portion of the cathode 22 is impregnated with the melted resin of the inner marginal portion of the resin frame member 24 to join the resin frame member 24 to the cathode 22 . thus , in comparison with the case where the resin frame member 24 is joined to the cathode 22 by adhesion , the joining strength for joining the resin frame member 24 to the cathode 22 is improved suitably , and it is possible to suppress occurrence of peeling or the like as much as possible . further , since the resin frame member 24 is joined only to the cathode 22 , the portion of the resin frame member 24 where heat contraction occurs is reduced , and it becomes possible to suppress occurrence of warpage or the like of the resin frame member 24 . in particular , the heating treatment is applied only to the overlapped portions in a concentrated manner by laser heating using the laser machine 56 . therefore , since the resin frame member 24 is heated only locally , the time required for melting is reduced . accordingly , cost reduction is achieved , and deformation is reduced as much as possible . it should be noted that infrared welding , impulse welding or the like may be adopted instead of laser welding using the laser machine 56 . firstly , as shown in fig1 , an oxygen - containing gas is supplied to the oxygen - containing gas supply passage 30 a , and a fuel gas such as a hydrogen - containing gas is supplied to the fuel gas supply passage 34 a . further , coolant such as pure water , ethylene glycol , or oil is supplied to the coolant supply passage 32 a . thus , the oxygen - containing gas flows from the oxygen - containing gas supply passage 30 a to the oxygen - containing gas flow field 36 of the second separator 16 . the oxygen - containing gas moves in the direction indicated by the arrow b , and the oxygen - containing gas is supplied to the cathode 22 of the membrane electrode assembly 10 . in the meanwhile , the fuel gas flows from the fuel gas supply passage 34 a through the supply holes 46 into the fuel gas flow field 38 of the first separator 14 . the fuel gas flows along the fuel gas flow field 38 in the direction indicated by the arrow b , and the fuel gas is supplied to the anode 20 of the membrane electrode assembly 10 . thus , in each of the membrane electrode assemblies 10 , the oxygen - containing gas supplied to the cathode 22 and the fuel gas supplied to the anode 20 are partially consumed in the electrochemical reactions in the electrode catalyst layers for generating electricity . then , the oxygen - containing gas partially consumed at the cathode 22 flows along the oxygen - containing gas discharge passage 30 b , and the oxygen - containing gas is discharged in the direction indicated by the arrow a . likewise , the fuel gas partially consumed at the anode 20 flows through the discharge holes 48 . then , the fuel gas flow along the fuel gas discharge passage 34 b , and the fuel gas is discharged in the direction indicated by the arrow a . further , the coolant supplied to the coolant supply passage 32 a flows into the coolant flow field 40 between the first separator 14 and the second separator 16 . then , the coolant flows in the direction indicated by the arrow b . after the coolant cools the membrane electrode assembly 10 , the coolant is discharged into the coolant discharge passage 32 b . fig7 is a diagram showing steps of a method of producing the membrane electrode assembly 10 according to a second embodiment of the present invention . in the second embodiment , the intermediate layer 20 b is coated on the gas diffusion layer of the anode ( s 1 ), and the intermediate layer 22 b is coated on the gas diffusion layer 22 c of the cathode ( s 2 ). the resin frame member 24 formed by injection molding beforehand is joined to the gas diffusion layer 22 c ( s 3 ). the process of joining the gas diffusion layer 22 c of the cathode 22 to the resin frame member 24 is substantially the same as in the case of the first embodiment . for example , the gas diffusion layer 22 c and the resin frame member 24 are joined together by placing the gas diffusion layer 22 c on the base table 52 shown in fig6 . in this manner , the resin frame member 24 and the gas diffusion layer 22 c of the cathode 22 are combined into one piece by the impregnation portion 26 . the electrode catalyst layers 20 a , 22 a are coated on both surfaces 18 a , 18 b of the solid polymer electrolyte membrane 18 ( s 4 ). further , the gas diffusion layer 20 c of the anode and the gas diffusion layer 22 c joined to the resin frame member 24 are placed on both surfaces 18 a , 18 b of the solid polymer electrolyte membrane 18 , respectively . these components are subjected to hot pressing treatment to produce the membrane electrode assembly 10 ( s 5 ). accordingly , in the second embodiment , the same advantages as in the case of the first embodiment are obtained . fig8 is a diagram showing steps of a method of producing a membrane electrode assembly 10 according to a third embodiment of the present invention . in the third embodiment , after the intermediate layer 20 b is coated on the gas diffusion layer 20 c of the anode ( s 11 ), the electrode catalyst layer 20 a is coated on the intermediate layer 20 b of the gas diffusion layer 20 c ( s 12 ). further , after the intermediate layer 22 b is coated on the gas diffusion layer 22 c of the cathode ( s 13 ), the resin frame member 24 is joined to the gas diffusion layer 22 c ( s 14 ). the process of joining the gas diffusion layer 22 c to the resin frame member 24 is the same as in the cases of the first and second embodiments . further , the electrode catalyst layer 22 a of the cathode is coated on the surface 18 b of the solid polymer electrolyte membrane 18 ( s 15 ). then , the gas diffusion layer 20 c of the anode and the gas diffusion layer 22 c of the cathode joined to the resin frame member 24 are placed on both surfaces 18 a , 18 b of the solid polymer electrolyte membrane 18 , respectively . these components are subjected to hot pressing treatment to produce the membrane electrode assembly 10 ( s 16 ). accordingly , in the third embodiment , the same advantages as in the cases of the first and second embodiments are obtained . fig9 is a cross sectional view showing a solid polymer electrolyte fuel cell 62 including a membrane electrode assembly 60 according to a fourth embodiment of the present invention . the constituent elements of the solid polymer electrolyte fuel cell 62 that are identical to those of the solid polymer electrolyte fuel cell 12 including the membrane electrode assembly 10 according to the first embodiment are labeled with the same reference numerals , and descriptions thereof will be omitted . likewise , also in fifth and subsequent embodiments described later , the constituent elements that are identical to those of the solid polymer electrolyte fuel cell 12 including the membrane electrode assembly 10 according to the first embodiment are labeled with the same reference numerals , and descriptions thereof will be omitted . in the membrane electrode assembly 60 , the anode 20 includes an electrode catalyst layer 20 a joined to the surface 18 a of the solid polymer electrolyte membrane 18 and a gas diffusion layer 20 c stacked on the electrode catalyst layer 20 a . the cathode 22 includes an electrode catalyst layer 22 a joined to the surface 18 b of the solid polymer electrolyte membrane 18 and a gas diffusion layer 22 c stacked on the electrode catalyst layer 22 a . though not shown , the electrode catalyst layer 20 a and the gas diffusion layer 20 c may be provided through an intermediate layer ( underlying layer ). likewise , the electrode catalyst layer 22 a and the gas diffusion layer 22 c may be provided through an intermediate layer ( underlying layer ). the resin frame member 24 and the gas diffusion layer 22 c of the cathode 22 are combined into one piece by a first resin impregnation portion 26 a , and the resin frame member 24 and the gas diffusion layer 20 c of the anode 20 are combined into one piece by a second resin impregnation portion 26 b . as shown in fig1 , the first resin impregnation portion 26 a is formed over the entire circumference of the gas diffusion layer 22 c of the cathode 22 . the width l 1 on the long side of the first resin impregnation portion 26 a ( side extending in the direction indicated by the arrow b ) is larger than the width l 2 on the short side of the first resin impregnation portion 26 a ( side extending in the direction indicated by the arrow c ) ( l 1 & gt ; l 2 ). as shown in fig1 , the second resin impregnation portion 26 b is formed over the entire circumference of the gas diffusion layer 20 c of the anode 20 . the width l 3 on the long side of the second resin impregnation portion 26 b ( side extending in the direction indicated by the arrow b ) is larger than the width l 4 on the short side of the second resin impregnation portion 26 b ( side extending in the direction indicated by the arrow c ) ( l 3 & gt ; l 4 ). as shown in fig9 , the second resin impregnation portion 26 b is terminated at a position spaced outward of a first inner circumferential portion 24 c of the resin frame member 24 adjacent to the cathode 22 by the distance h . that is , the second resin impregnation portion 26 b is not provided at a position overlapped with the cathode 22 in the stacking direction . next , a method of producing the membrane electrode assembly 60 will be described below . firstly , as shown in fig1 , an mea 64 having different sizes of components ( stepped - type mea ) of the membrane electrode assembly 60 is produced . specifically , the electrode catalyst layers 20 a , 22 a are coated on both surfaces 18 a , 18 b of the solid polymer electrolyte membrane 18 . the gas diffusion layer 20 c is placed adjacent to the surface 18 a of the solid polymer electrolyte membrane 18 , i . e ., on the electrode catalyst layer 20 a , and the gas diffusion layer 22 c is placed adjacent to the surface 18 b of the solid polymer electrolyte membrane 18 , i . e ., on the electrode catalyst layer 22 a . these components are stacked together , and subjected to hot pressing treatment to produce the mea 64 . in the meanwhile , the resin frame member 24 is formed beforehand by an injection molding machine ( not shown ). the resin frame member 24 is positioned in alignment with the mea 64 . the resin frame member 24 has the first inner circumferential portion 24 c and a second inner circumferential portion 24 d . the end of the cathode 22 is positioned at the first inner circumferential portion 24 c , and the end of the anode 20 is positioned at the second inner circumferential portion 24 d . a first resin member 26 aa forming the first resin impregnation portion 26 a is prepared at the cathode 22 , and a second resin member 26 bb forming the second resin impregnation portion 26 b is prepared at the anode 20 . each of the first resin member 26 aa and the second resin member 26 bb has a frame shape , and is made of the same material as the resin frame member 24 , for example . the resin frame member 24 uses resin material enforced by mixing a filler with the resin material . the first resin member 26 aa and the second resin member 26 bb may be made of resin material which is not mixed with any filler . in the structure , using the robust resin frame member 24 , the mea 64 and the resin frame member 24 can be joined together . then , in the state where the first resin member 26 aa and the second resin member 26 bb are placed over the mea 64 and the resin frame member 24 and a load is applied to the mea 64 and the resin frame member 24 through the first resin member 26 aa and the second resin member 26 bb , the first resin member 26 aa and the second resin member 26 bb are heated . as a heating method , any of laser welding , infrared welding , and impulse welding , etc . is adopted . thus , the first resin member 26 aa and the second resin member 26 bb are melted by heating . both of the gas diffusion layer 22 c of the cathode 22 and the resin frame member 24 are impregnated with the melted resin of the first resin member 26 aa , and both of the gas diffusion layer 20 c of the anode 20 and the resin frame member 24 are impregnated with the melted resin of the second resin member 26 bb . thus , as shown in fig9 , the first resin impregnation portion 26 a is formed over the gas diffusion layer 22 c of the cathode 22 and the resin frame member 24 , and the second resin impregnation portion 26 b is formed over the gas diffusion layer 20 c of the anode 20 and the resin frame member 24 to produce the membrane electrode assembly 60 . in the fourth embodiment , the outer ends of the gas diffusion layers 22 c , 20 c of the cathode 22 and the anode 20 and the resin frame member 24 are impregnated with resin , respectively , and formed integrally with the first resin impregnation portion 26 a and the second resin impregnation portion 26 b . in the structure , in comparison with the case where the resin frame member 24 is joined to the cathode 22 and the anode 20 by adhesion , the joining strength for joining the resin frame member 24 to the cathode 22 and the anode 20 is improved suitably , and it is possible to suppress occurrence of peeling or the like as much as possible . further , the width l 1 on the long side of the first resin impregnation portion 26 a is larger than the width l 2 on the short side of the first resin impregnation portion 26 a ( l 1 & gt ; l 2 ) ( see fig1 ). moreover , the width l 3 on the long side of the second resin impregnation portion 26 b is larger than the width l 4 on the short side of the second resin impregnation portion 26 b ( l 3 & gt ; l 4 ) ( see fig1 ). thus , further improvement in the joining strength for joining the resin frame member 24 to the cathode 22 and the anode 20 is achieved suitably , further , as shown in fig9 , the second resin impregnation portion 26 b is terminated at a position spaced outward of the first inner circumferential portion 24 c of the resin frame member 24 adjacent to the cathode 22 , by the distance h . in the range of the distance h , since the electrode catalyst layer 22 a of the cathode 22 facing the anode 20 is not present , abnormal reaction does not occur . for example , in a comparative example shown in fig1 , the gas diffusion layer 22 c of the cathode 22 and the resin frame member 24 are combined into one piece by a first resin impregnation portion 27 a . further , the gas diffusion layer 20 c of the anode 20 and the resin frame member 24 are combined into one piece by a second resin impregnation portion 27 b . the second resin impregnation portion 27 b extends inward of the end of the first resin impregnation portion 27 a by the distance ha . in the comparative example , the electrode catalyst layer 22 a of the cathode 22 is present in the range of the distance ha where the second resin impregnation portion 27 b is provided . in the structure , shortage of hydrogen occurs at the anode 20 in the range of the distance ha , and abnormal reaction tends to occur at the cathode 22 . specifically , by reactions of h 2 o → 1 / 2o 2 + 2h + + 2e − , c + 2h 2 o → co 2 + 4h + + 4e − , and pt → pt 2 + + 2e − , dissolution of corrosive pt of the supporting carbon occurs , and consequently , the performance is lowered undesirably . fig1 is a cross sectional view showing main components of a membrane electrode assembly 70 according to a fifth embodiment of the present invention . the membrane electrode assembly 70 includes a resin frame member 72 joined to the cathode 22 and the anode 20 . a first resin protrusion 74 a and a second resin protrusion 74 b are formed integrally with the resin frame member 72 for combining the resin frame member 72 and the gas diffusion layer 22 c of the cathode 22 into one piece , and combining the resin frame member 72 and the gas diffusion layer 20 c of the anode 20 into one piece . the first resin protrusion 74 a is formed in a frame shape around the first inner circumferential portion 24 c , and the second resin protrusion 74 b is formed in a frame shape around the second inner circumferential portion 24 d . preferably , the first resin protrusion 74 a has an inclined surface 74 as as an end surface opposite to the first inner circumferential portion 24 c , and the inclined surface 74 as is inclined in a direction spaced from the resin frame member 72 . likewise , preferably , the second resin protrusion 74 b has an inclined surface 74 bs as an end surface opposite to the second inner circumferential portion 24 d , and the inclined surface 74 bs is inclined in a direction spaced from the resin frame member 72 . the first resin protrusion 74 a and the second resin protrusion 74 b are heated by a heating machine ( not shown ), and melted . by applying a load to the first resin protrusion 74 a and the second resin protrusion 74 b , the gas diffusion layers 22 c , 20 c are impregnated with the melted resin of the first resin protrusion 74 a and the second resin protrusion 74 b . in this manner , the first resin impregnation portion 26 a and the second resin impregnation portion 26 b are formed . thus , in the fifth embodiment , the same advantages as in the case of the fourth embodiment are obtained . fig1 is a cross sectional view showing main components of a membrane electrode assembly 80 according to a sixth embodiment of the present invention . the membrane electrode assembly 80 includes a resin frame member 82 joined to the cathode 22 and the anode 20 . the resin frame member 82 includes a first resin member 84 a and a second resin member 84 b for combining the resin frame member 82 and the gas diffusion layer 22 c of the cathode 22 into one piece , and combining the resin frame member 82 and the gas diffusion layer 20 c of the anode 20 into one piece . the first resin member 84 a and the second resin member 84 b are formed integrally with the resin frame member 82 by insert molding beforehand . the first resin member 84 a and the second resin member 84 b are heated by a heating machine ( not shown ), and melted . by applying a load to the first resin member 84 a and the second resin member 84 b , the gas diffusion layers 22 c , 20 c are impregnated with the melted resin of the first resin member 84 a and the second resin member 84 b . in this manner , the first resin impregnation portion 26 a and the second resin impregnation portion 26 b are formed . thus , in the sixth embodiment , the same advantages as in the case of the fourth and fifth embodiments are obtained . fig1 is a cross sectional view showing a membrane electrode assembly 90 according to a seventh embodiment of the present invention . the membrane electrode assembly 90 includes a resin frame member 92 joined to the cathode 22 and the anode 20 . a first resin protrusion 94 a and a second resin protrusion 94 b are provided integrally with the resin frame member 92 for combining the resin frame member 92 and the gas diffusion layer 22 c of the cathode 22 into one piece , and combining the resin frame member 92 and the gas diffusion layer 20 c of the anode 20 into one piece . the first resin protrusion 94 a is formed in a frame shape around the first inner circumferential portion 24 c , and the second resin protrusion 94 b is formed in a frame shape around the second inner circumferential portion 24 d . each of the first resin protrusion 94 a and the second resin protrusion 94 b has a rectangular shape in cross section . in effect , the first resin protrusion 94 a and the second resin protrusion 94 b are formed by eliminating the inclined surfaces 74 as , 74 bs of the first resin protrusion 74 a and the second resin protrusion 74 b in the membrane electrode assembly 70 according to the fifth embodiment . in the seventh embodiment , the first resin protrusion 94 a and the second resin protrusion 94 b are heated by a heating machine ( not shown ), and melted . by applying a load to the first resin protrusion 94 a and the second resin protrusion 94 b , the gas diffusion layers 22 c , 20 c are impregnated with the melted resin of the first resin protrusion 94 a and the second resin protrusion 94 b . in this manner , the first resin impregnation portion 26 a and the second resin impregnation portion 26 b are formed . thus , in the seventh embodiment , the same advantage as in the case of the fourth to sixth embodiments are obtained . further , in particular , operation of producing the first resin protrusion 94 a and the second resin protrusion 94 b can be carried out simply . fig1 is a cross sectional view showing a solid polymer electrolyte fuel cell 102 including a membrane electrode assembly 100 according to an eighth embodiment of the present invention . in the membrane electrode assembly 100 , the resin frame member 24 and the gas diffusion layer 20 c of the anode 20 are combined into one piece by a resin impregnation portion 104 . that is , the resin frame member 24 is joined only to the anode 20 which is larger than the cathode 22 . at the time of producing the membrane electrode assembly 100 , as shown in fig1 , an mea 106 having different sizes of components ( stepped - type mea ) of the membrane electrode assembly 100 is produced . in the state where the resin frame member 24 and the mea 106 are positioned with respect to each other , a resin member 104 a for forming the resin impregnation portion 104 is prepared . the resin member 104 a has a frame shape , and uses resin material enforced by mixing a glass filler with the resin material . then , in the state where the resin member 104 a is placed , and a load is applied to the mea 106 and the resin frame member 24 , the resin member 104 a is heated . thus , the heated resin member 104 a is melted to form the resin impregnation portion 104 over the gas diffusion layer 20 c of the anode 20 and the resin frame member 24 . in this manner , the membrane electrode assembly 100 is produced . in the eighth embodiment , when the resin member 104 a is heated , and melted , the glass filler does not enter the gas diffusion layer 20 c . therefore , the resin member 104 a does not directly contact the solid polymer electrolyte membrane 18 . further , when the resin member 104 a is melted at high temperature , the gas diffusion layer 20 c and the electrode catalyst layer 20 a , and in certain cases , an intermediate layer 20 b are present between the solid polymer electrolyte membrane 18 and the resin member 104 a . thus , thermal effect on the solid polymer electrolyte membrane 18 is reduced . accordingly , as the resin member 104 a , it become possible to adopt resin mixed with a glass filler , and use resin having high melting temperature . thus , the resin used for the resin member 104 a can be adopted from a wide variety of selection advantageously .