when a support member that is pivotable with respect to a housing is rotated and held at a certain angle to restrain the rotation , it is desired to improve the workability of working . fig1 illustrates an example of a computer . fig2 is an exploded perspective view of a computer . the computer may be an electronic apparatus . external devices such as input / output devices and storage units and a communication line are coupled to a computer body 12 as desired . the computer body 12 includes a housing 14 . the housing 14 includes a housing body 16 having a bottom wall 16 b , a front wall 16 f , a rear wall 16 r , and side walls 16 a and 16 c , and includes a cover 18 that covers the housing body 16 . in descriptions below , the “ front side ” and “ rear side ” are respectively the front side ( indicted by the arrow fr ) and the rear side ( opposite to the side indicated by the arrow fr ) with respect to the housing 14 . the “ front - and - rear direction ”, “ upper direction ”, and “ width direction ” are the front - and - rear direction , upper direction ( indicated by the arrow up ), and width direction ( indicated by the arrow w ) with respect to the housing 14 . although , in fig1 to 12 , the computer body 12 is placed such that the width direction is aligned with a horizontal direction ( placed sideways ), the computer body 12 may be placed such that the width direction is aligned with the vertical direction ( placed upright ) according to the usage status . the width direction and front - and - rear direction of individual structures may be interchanged ( the structures may be oriented in a direction rotated by 90 degrees ) depending on the structure of the computer body 12 . a mounting member 20 is mounted on the housing body 16 so as to be pivotable between a falling position ( see fig8 a , 8 b , and 8 c ) and an erected position ( see fig1 a , 11 b , and 11 c ) with respect to the housing 14 . in fig2 , 8 a , 8 b , and 8 c , the arrow r1 indicates the direction in which the mounting member 20 is rotated from the falling position to the erected position . an attachment unit 22 is provided in the mounting member 20 . a mounted member 62 to be mounted in the computer body 12 is attached to the attachment unit 22 . the mounted member 62 may include , for example , an optical disk drive 62 a and a hard disk drive 62 b . the mounting member 20 has an attachment unit 22 a , in which the optical disk drive 62 a is attached , and an attachment unit 22 b , in which the hard disk drive 62 b is attached . the mounted member 62 attached to the mounting member 20 is not limited to the optical disk drive 62 a and hard disk drive 62 b . a fixing piece 26 is secured to the side wall 16 a on one side of the housing body 16 with a fastener or the like . the fixing piece 26 , which is made of a metal plate , is formed into a desired form by making a slit at certain position of a metal plate , bending the metal plate , and machining such as perforating the metal plate . in machining on the metal plate , pressing , cutting , punching , laser beam irradiation , and the like may be appropriately combined . the fixing piece 26 is positioned so that a body 26 a is oriented in the front - and - rear direction of the housing 14 . fig3 , 4 , and 5 are exploded perspective views of a housing and mounting member of a computer . as illustrated in fig3 and 4 , holding plates 28 and 30 , which are formed by bending the metal plate of the body 26 a in the width direction of the housing 14 , are respectively formed on the front side and rear side of the fixing piece 26 . holding holes 32 and 34 are respectively formed at the top of the holding plates 28 and 30 to pass through the holding plates 28 and 30 in the thickness direction , for example , a direction aligned with the front - and - rear direction of the housing 14 . the holding hole 32 in the holding plate 28 on the front side is formed in a perfect circular shape and has a female screw in its inner circumference . the holding hole 34 in the holding plate 30 on the rear side is substantially l - shaped and has a horizontal part 34 a which is a long hole extending in the width direction , and a vertical part 34 b which is formed long on the side wall 16 a side to extend downward from the horizontal part 34 a . fig6 and 7 are perspective views of a mounting member of a computer . as illustrated in fig6 and 7 , a side plate 24 is formed on the side wall 16 a side of the mounting member 20 to extend downward . in the front - and - rear direction , the length of the side plate 24 is substantially the same as the length of the mounting member 20 . the side plate 24 has an upper plate 38 extending in the front - and - rear direction at the top , and has a front plate 40 and a rear plate 42 respectively extending from the front end and the rear end in the width direction . a support shaft 44 is formed at an upper portion of the rear plate 42 and extends toward the rear side . as illustrated in fig4 , the support shaft 44 is inserted into the holding hole 34 from the front side . a shaft hole 46 , which passes through the front plate 40 in its thickness direction , is formed at an upper portion of the front plate 40 . the shaft hole 46 is substantially l - shaped and has a horizontal part 46 a which is a long hole extending in the width direction , with the mounting member 20 in the falling state , and a vertical part 46 b , which is formed long on the side wall 16 a side to extend downward from the horizontal part 46 a . with the shaft hole 46 and holding hole 32 aligned , a shaft screw 48 is inserted into the shaft hole 46 and is screwed in the female screw of the holding hole 32 , as illustrated in fig3 . in this state , the axial line x1 ( see fig3 ) of the shaft screw 48 is aligned with the axial line x2 ( see fig4 ) of the support shaft 44 . for example , the mounting member 20 is mounted by the support shaft 44 on the rear side and by the shaft screw 48 on the front side so as to be pivotable around a rotation center line c1 ( see fig5 ) with respect to the housing 14 . the support shaft 44 and shaft screw 48 may be a pivot shaft of the mounting member 20 . the shaft screw 48 may be , for example , a shoulder screw ; an amount by which the shaft screw 48 is screwed in the holding hole 32 may be restricted within a certain range . accordingly , a clearance equal to or larger than the thickness of the front plate 40 is left between the holding plate 28 and the head of the shaft screw 48 , and undesirable resistance against the rotation of the mounting member 20 may not be caused . the housing 14 has a clamping part 50 that partially clamps the mounting member 20 positioned at the falling position to restrain undesirable rotation of the mounting member 20 . when the mounting member 20 is pulled up toward the erected position against the clamping force of the clamping part 50 , the mounting member 20 may be unclamped . with the clamping part 50 in an unclamped state , the mounting member 20 becomes pivotable toward the erected position . fig8 a is an a - a line cross sectional view when a mounting member is at the falling position . fig8 b is a b - b line cross sectional view when the mounting member is at the falling position . fig8 c is a c - c line cross sectional view when the mounting member is at the falling position . a - a line , b - b line , and c - c line are indicated in fig5 . as illustrated in fig8 a , when the mounting member 20 is at the falling position , the shaft hole 46 is positioned at the bottom of the vertical part 46 b with respect to the shaft screw 48 as illustrated in fig8 a ; for example , the shaft hole 46 is positioned at a high position relative to the position of the shaft screw 48 . at the horizontal part 34 a , the support shaft 44 is positioned on the side wall 16 a side . when the mounting member 20 is supported by , for example , a curved support edge 52 b , a state may be maintained in which the shaft screw 48 is positioned at the bottom of the vertical part 46 b and the support shaft 44 is positioned in the horizontal part 34 a on the side wall 16 a side . as illustrated in fig3 and 4 , the fixing piece 26 has one or a plurality of support pieces 52 . three support pieces 52 are formed with a space between each two support pieces 52 in the front - and - rear direction . the support piece 52 may be an example of a support member . the top of each support piece 52 is a wide portion 52 a , which is wide toward the side wall 16 a . the upper end of the wide portion 52 a is the curved support edge 52 b , which is curved to have an upward convex . the curved support edge 52 b is curved so that when the mounting member 20 is rotated from the falling position toward the erected position , the curved support edge 52 b supports the upper plate 38 of the mounting member 20 from below to guide the rotation of the mounting member 20 until an intermediate position in the rotation is reached . grooves 24 b are formed in the side plate 24 and upper plate 38 of the mounting member 20 at positions corresponding to the curved support edges 52 b in the front - and - rear direction . fig9 a is an a - a line cross sectional view when a mounting member is rotated . fig9 b is a b - b line cross sectional view when a mounting member is rotated . fig9 c is a c - c line cross sectional view when a mounting member is rotated . a - a line , b - b line , and c - c line are indicated in fig5 . when the mounting member 20 is rotated from the falling position toward the erected position , the grooves 24 b are displaced toward the outside in the width direction until a rotation angle reaches a certain angle ( see fig9 a , 9 b , and 9 c ). therefore , the mounting member 20 may be supported at the side plate 24 and upper plate 38 by the curved support edges 52 b , and the downward motion of the mounting member 20 may be restricted . a state is maintained in which the shaft hole 46 is positioned at the bottom of the vertical part 46 b with respect to the shaft screw 48 and the shaft screw 48 is positioned at the bottom of the vertical part 46 b . if the rotation angle to the erected position of the mounting member 20 exceeds the above certain angle , the grooves 24 b move toward the inside in the width direction and reach the top of the curved support edges 52 b . the curved support edges 52 b are placed in the grooves 24 b and no longer support the mounting member 20 . this position at which the mounting member 20 is not supported may be referred to as a support cancel position . as illustrated in fig9 a , the shaft screw 48 is positioned at the top end of the horizontal part 46 a , which is inclined in this state , and there is a clearance g between the shaft hole 46 and the top of the shaft screw 48 . the support shaft 44 is positioned on a boundary between the horizontal part 34 a and the vertical part 34 b , and there is a clearance between the holding hole 34 and the bottom of the support shaft 44 . fig1 a is an a - a line cross sectional view when a mounting member is rotated . fig1 b is a b - b line cross sectional view when the mounting member is rotated . fig1 c is a c - c line cross sectional view when the mounting member is rotated . a - a line , b - b line , and c - c line are indicated in fig5 . as illustrated in , for example , fig1 b and 10c , the curved support edges 52 b do not support the mounting member 20 ( the side plate 24 and upper plate 38 ). accordingly , the mounting member 20 is able to be displaced downward . if the mounting member 20 is at , for example , the erected position , the mounting member 20 may be displaced in a direction crossing the rotation center line c1 , for example , in a downward direction orthogonal to the rotation center line c1 . the holding hole 32 and shaft hole 46 may be an example of an accommodating hole . when the mounting member 20 is at the erected position , the shaft screw 48 and holding hole 32 , and the support shaft 44 and shaft hole 46 may be displaced in a direction crossing the rotation center line c1 , for example , in a direction orthogonal to the rotation center line c1 , and may be an example of a displacing member . the fixing piece 26 has one or a plurality of guide pieces 56 . for example , four guide pieces 56 may be formed with a space between the guide pieces 56 in the front - and - rear direction . the guide piece 56 and support piece 52 are displaced in the front - and - rear direction . as illustrated in fig8 b and 8c , when the fixing piece 26 is viewed in the front - and - rear direction , a retaining part 58 , which is slightly wider than the thickness of the upper plate 38 in the width direction , is formed between a widthwise inner side 56 s of the guide piece 56 and a widthwise outer side 52 s of the support piece 52 . the positions and shapes of the guide piece 56 and support piece 52 are determined so that the retaining part 58 , which is slightly wider than the thickness of the upper plate 38 , is formed , for example , between the guide piece 56 and the support piece 52 . fig1 a is an a - a line cross sectional view when a mounting member is at an erected position . fig1 b is a b - b line cross sectional view when a mounting member is at an erected position . fig1 c is a c - c line cross sectional view when a mounting member is at an erected position . a - a line , b - b line , and c - c line are indicated in fig5 . as illustrated in fig1 b and 11c , with the upper plate 38 inserted into the retaining part 58 , the motion of the upper plate 38 in the width direction is restricted , so the rotation of the mounting member 20 is also suppressed . with the mounting member 20 at the erected position , a direction , indicated by the arrow m1 , in which the upper plate 38 extends and a direction in which the upper plate 38 is inserted into the retaining part 58 are aligned with the displacement direction ( downward direction ) of the mounting member 20 . the upper plate 38 may be an example of a retained member . the retaining part 58 and upper plate 38 may be an example of a rotation suppressing member . at the top end of the guide piece 56 , a guide edge 56 a , which is shaped to be lowered from the side wall 16 a side toward the inside in the width direction , is formed . the upper plate 38 of the mounting member 20 has a non - contact concave part 60 at a position corresponding to the guide piece 56 in the front - and - rear direction . the non - contact concave part 60 is formed at a position at which the non - contact concave part 60 does not contact with the guide piece 56 as illustrated in fig9 c until the rotation angle reaches a certain angle , when the mounting member 20 is further rotated from the support cancel position toward the erected position . when the rotation angle to the erected position of the mounting member 20 exceeds the above certain angle , the bottom edge 60 a of the non - contact concave part 60 contacts with the guide edge 56 a . when the mounting member 20 is further rotated toward the erected position , the bottom edge 60 a slides downward and inside in the width direction along the guide edge 56 a . therefore , due to the rotation of the mounting member 20 , the upper plate 38 is displaced downward while rotating and is guided to the retained position as indicated by the arrow m1 in fig9 c , and is guided to a retained position at which the upper plate 38 is retained by the retaining part 58 . the contact position at which the upper plate 38 contacts with the guide edge 56 a may be referred to as a guide start position . the guide piece 56 may be an example of a guide member . when the cover 18 has been attached to the housing 14 as illustrated in fig1 , the cover 18 is removed from the housing 14 . in a factory or the like where the computer body 12 is manufactured , operation of rotating the mounting member 20 may be performed in the housing 14 to which the cover 18 has not been attached . when the mounting member 20 is at the falling position as illustrated in fig8 a , 8 b , and 8 c , the upper plate 38 is supported by the curved support edge 52 b ( see fig8 b and 8c ). therefore , a state is maintained in which the shaft hole 46 is positioned at the bottom of the vertical part 46 b with respect to the shaft screw 48 ( see fig8 a ) and the shaft screw 48 is positioned at the bottom of the vertical part 46 b . to rotate the mounting member 20 to the erected position , the mounting member 20 is pulled up toward the erected position against the clamping force of the clamping part 50 to cancel the clamping . when the mounting member 20 is rotated in the direction indicated by the arrow r1 toward the erected position , the curved support edge 52 b supports the upper plate 38 and side plate 24 of the mounting member 20 from below until the mounting member 20 reaches the support cancel position ( see fig9 b and 9c ). since the upper plate 38 of the mounting member 20 slides on the curved support edge 52 b , undesirable downward movement , for example , is suppressed during the rotation of the mounting member 20 , enabling smooth rotation . when the mounting member 20 is rotated toward the erected position and reaches the support cancel position , the curved support edge 52 b enters the groove 24 b and the support of the mounting member 20 by the curved support edge 52 b is canceled ( see fig1 b and 10c ). the clearance g ( see fig9 a ) is formed between the shaft screw 48 and the shaft hole 46 . a clearance is also formed between the holding hole 32 and the bottom of the support shaft 44 . since the curved support edge 52 b does not support the mounting member 20 , the mounting member 20 is movable downward . when the mounting member 20 is further rotated toward the erected position , since the non - contact concave part 60 is formed in the mounting member 20 , the mounting member 20 ( the bottom edge 60 a of the non - contact concave part 60 ) does not interfere ( contact ) with the guide piece 56 until the mounting member 20 reaches the guide start position . for example , the rotation of the mounting member 20 may not be restricted by the guide piece 56 or undesirable resistance may not be generated in the rotation . with the mounting member 20 at the guide start position , the upper plate 38 ( the bottom edge 60 a of the non - contact concave part 60 ) contacts with the guide piece 56 . when the mounting member 20 is further rotated from the guide start position toward the erected position , due to the rotation of the mounting member 20 , the upper plate 38 moves downward and inside in the width direction while rotating as indicated by the arrow m1 in fig9 c . therefore , due to the rotation of the mounting member 20 , the rotation center line c1 ( see fig5 ) of the mounting member 20 moves downward and inside in the width direction , and the upper plate 38 is guided to the retained position at which it is retained by the retaining part 58 . the mounting member 20 reaches the erected position as illustrated in fig1 a , 11 b , and 11 c . at that time , the upper plate 38 is retained in the retaining part 58 ( see fig1 b and 11c ). thus , the rotation of the mounting member 20 is suppressed . even if , for example , the force with which the mounting member 20 is supported is removed , undesirable falling to the falling position of the mounting member 20 is suppressed . due to the rotation of the mounting member 20 , the rotation center line c1 is displaced . due to the displacement of the mounting member 20 , part ( the upper plate 38 ) of the mounting member 20 may be retained at the erected position of the mounting member 20 and the rotation of the mounting member 20 may be suppressed . special operation to suppress the rotation of the mounting member 20 may not be desired . workability may be improved . a new member , for example , a member placed between the mounting member 20 and the housing 14 is not desired to suppress the rotation of the mounting member 20 at the erected position and the number of parts is reduced . since the shaft hole 46 and holding hole 34 are substantially l - shaped , when the mounting member 20 moves downward , the upper plate 38 is retained in the retaining part 58 , and the rotation of the mounting member 20 is suppressed . since part of the mounting member 20 is retained and its rotation is suppressed , the pull - up of the mounting member 20 or its movement in the width direction , for example , may not be desired . workability may be improved . the holding hole 32 and shaft hole 46 are substantially l - shaped . when the mounting member 20 is rotated from the guide start position to the falling position , the bottom edge 60 a of the upper plate 38 is guided by the guide edge 56 a , and the upper plate 38 is displaced in a direction indicated by the arrow m1 ( see fig9 c ). due to the displacement of the upper plate 38 in a direction in which it is drawn toward the inside in the width direction , undesirable interference with the housing 14 ( the side wall 16 a , the fixing piece 26 , and the like ) may be suppressed during the rotation of portions of the mounting member 20 other than the bottom edge 60 a . in a structure in which , for example , the housing 14 is made small and various members are placed therein at a high density , interference between the mounting member 20 and the various members may be suppressed during the rotation of the mounting member 20 , the mounting member 20 may be held at the erected position , and the falling of the mounting member 20 may be suppressed . in a simplified structure in which the holding hole 34 is formed in the housing 14 and the shaft hole 46 is formed in the mounting member 20 , the mounting member 20 may be capable of moving in a direction crossing ( in the above example , orthogonal to ) the rotation center line c1 with the mounting member 20 at the erected position . when the upper plate 38 is retained in the retaining part 58 , the direction in which the mounting member 20 is displaced and the direction in which the upper plate 38 extends from the mounting member 20 ( the direction indicated by the arrow m1 ) may be the same as illustrated in fig1 b and 11c . since the upper plate 38 is retained , for example , in the retaining part 58 so as to be inserted into the retaining part 58 along the direction in which the upper plate 38 extends , the width of the retaining part 58 , for example , may be reduced within a range in which the upper plate 38 is able to be retained , for example , to about the thickness of the upper plate 38 . when the mounting member 20 is at the erected position , the mounted member 62 may be attached to or removed from the attachment unit 22 of the mounting member 20 . since the mounting member 20 is maintained at the erected position , attachment and removal may be easy . when the mounting member 20 is returned from the erected position to the falling position , the mounting member 20 at the erected position is displaced upward as illustrated in fig1 . due to this displacement , the upper plate 38 is no longer retained in the retaining part 58 . the mounting member 20 is rotated from the falling position to the erected position . since the mounting member 20 , for example , the upper plate 38 and side plate 24 are supported by the curved support edge 52 b of the support piece 52 , the mounting member 20 may be stably rotated . the rotation center line c1 of the mounting member 20 positioned at the erected position is displaced downward and inside of the falling position in the width direction , for example , in a direction crossing the rotation center line c1 . when part of the mounting member 20 is held , the displacement direction of the mounting member 20 may not be a direction crossing the rotation center line c1 . for example , at the erected position , the mounting member 20 may be displaced backward and a holding member that holds part of the mounting member 20 may be provided behind the mounting member 20 . in this structure , a space in which the holding member is placed is formed behind the mounting member 20 in the housing 14 . the space behind the mounting member 20 may be used to place various members and wires of the computer body 12 . when the mounting member 20 is displaced in a direction crossing ( particularly , orthogonal to ) the rotation center line c1 , since the mounting member 20 is not displaced backward , the space behind the mounting member 20 may be used to place other members . the support piece 52 ( support member ) and guide piece 56 ( guide member ) may be part of one fixing piece 26 . alternatively , the support member and guide member may be separately provided . if the support member and guide member are formed as part of one fixing piece 26 , the support member and guide member are integrated , so the number of parts may be reduced . if the fixing piece 26 is secured when it is secured to the housing 14 , the support member and guide member are also secured at the same time , so workability may be improved . since the support piece 52 ( support member ) and guide piece 56 ( guide member ) are formed as part of the fixing piece 26 by bending a single metal plate , the support member and guide member may not be integrated in a later process . the rotation of the mounting member 20 may be suppressed by retaining part of the mounting member 20 ( the upper plate 38 ) by the retaining part 58 ( the guide piece 56 and support piece 52 ). for example , when the mounting member 20 is at the erected position , part of the mounting member 20 may be engaged with the housing 14 to suppress the rotation of the mounting member 20 . when the rotation of the mounting member 20 is suppressed by retaining part of the mounting member 20 ( the upper plate 38 ), a member for engagement may not be used . the structure may be simplified . with the mounting member 20 at the erected position , the whole of the mounting member 20 in the thickness direction , rather than part ( the upper plate 38 ) of the mounting member 20 , may be retained . in a structure in which part ( the upper plate 38 ) of the mounting member 20 is retained , the retaining part 58 may be made small . an engaged part that an engaging part engages may not be provided on the mounting member 20 . the structure of the mounting member 20 may be simplified by forming a retained member ( the upper plate 38 ) retained in the retaining part 58 . the mounted member 62 may be the optical disk drive 62 a or hard disk drive 62 b . other various mounted members 62 attached and mounted in the housing 14 are also allowed . an electronic apparatus may be the computer body 12 ; may be , for example , a computer with an integrated display unit . an electronic apparatus may be a computer ; for example , a processing unit , or a recording and reproducing unit that handles electronic information ( including video , images , voice data , and the like ). all examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art , and are to be construed as being without limitation to such specifically recited examples and conditions , nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention . although the embodiments of the present invention have been described in detail , it should be understood that the various changes , substitutions , and alterations could be made hereto without departing from the spirit and scope of the invention .