reference will now be made in detail to the preferred embodiments of the present invention , examples of which are illustrated in the accompanying drawings . fig3 is a side sectional view showing a drum type washing machine according to one embodiment of the present invention , and fig4 is a front sectional view showing the drum type washing machine according to one embodiment of the present invention . the drum type washing machine according to one embodiment of the present invention comprises : a cabinet 2 for forming an appearance of a washing machine ; a tub 4 formed integrally with the cabinet 2 and for storing washing water ; a drum 6 rotatably arranged in the tub 4 for washing and dehydrating laundry ; and a driving motor 8 positioned at the rear side of the drum 6 for generating a driving force by which the drum 6 is rotated . the cabinet 2 is rectangular parallelepiped , and an inlet 20 for inputting and outputting laundry is formed at the front side of the cabinet 2 and a door 10 for opening and closing the inlet 20 is formed at the inlet 20 . the tub 4 is formed as a cylinder shape having a predetermined diameter in the cabinet 2 , and the front side of the tub 4 is fixed to the front inner wall of the cabinet 2 or integrally formed at the front inner wall of the cabinet 2 . both sides of the tub 4 are contacted to both sides inner wall of the cabinet 2 or integrally formed with both sides inner wall of the cabinet 2 thus to be prolonged . herein , since both sides of the tub 4 are contacted to both sides inner wall of the cabinet 2 , a diameter of the tub 4 can be increased . also , the supporting plate 12 is positioned at the rear side of the tub 4 and the gasket 14 is installed between the supporting plate 12 and the rear side of the tub 4 , thereby preventing washing water filled in the tub 4 from being leaked . the gasket 14 is formed as a bellows of a cylinder shape and has one side fixed to the rear side of the tub 4 and another side fixed to an outer circumference surface of the supporting plate 12 . the supporting plate 12 is formed as a disc shape , the driving motor 8 is fixed to the rear surface thereof , and a rotation shaft 16 for transmitting a rotation force of the driving motor 8 to the drum 6 is rotatably supported by the supporting plate 12 . also , a supporting unit for supporting the drum 6 with buffering is installed between the supporting plate 12 and the inner wall of the cabinet 2 . the supporting unit comprises : a plurality of upper supporting rods 22 connected to an upper side of the supporting plate 12 and having a predetermined length ; buffering springs 24 connected between the upper supporting rods 22 and an upper inner wall of the cabinet 2 for buffering ; a plurality of lower supporting rods 26 connected to a lower side of the supporting plate 12 and having a predetermined length ; and dampers 28 connected between the lower supporting rods 26 and a lower inner wall of the cabinet 2 for absorbing vibration . herein , the buffering springs 24 and the dampers 28 are installed at a center of gravity of an assembly composed of the drum 6 , the supporting plate 12 , and the driving motor 8 . that is , the upper and lower supporting rods 22 and 26 are prolonged from the supporting plate 12 to the center of gravity of the assembly , the buffering springs 24 are connected between an end portion of the upper supporting rod 22 and the upper inner wall of the cabinet 2 , and the dampers 28 are connected between an end portion of the lower supporting rod 26 and the lower inner wall of the cabinet 2 , thereby supporting the drum 6 at the center of gravity . a diameter of the drum 6 is installed in a range that the drum 6 is not contacted to the tub 4 even when the drum 6 generates maximum vibration in order to prevent interference with the tub 4 at the time of being rotated in the tub 4 . operations of the drum type washing machine according to the present invention are as follows . if the laundry is inputted into the drum 6 and a power switch is turned on , washing water is introduced into the tub 6 . at this time , the front side of the tub 6 is fixed to the cabinet 2 and the gasket 14 is connected between the rear side of the tub 6 and the supporting plate 12 , thereby preventing the washing water introduced into the tub 6 from being leaked outwardly . if the introduction of the washing water is completed , the driving motor 8 mounted at the rear side of the supporting plate 12 is driven , and the drum 6 connected with the driving motor 8 by the rotation shaft 16 is rotated , thereby performing washing and dehydration operations . at this time , the assembly composed of the drum 6 , the driving motor , and the supporting plate 12 is supported by the buffering springs 24 and the dampers 28 mounted between the supporting plate 12 and the inner wall of the cabinet 20 . fig6 is a front sectional view of a drum type washing machine according to a second embodiment of the present invention . the drum type washing machine according to the second embodiment of the present invention has the same construction and operation as that of the first to embodiment except a shape of the tub . that is , the tub 40 according to the second embodiment has a straight line portion 42 with a predetermined length at both sides thereof . the straight line portion 42 is fixed to the inner wall of both sides of the cabinet 2 , or integrally formed at the wall surface of both sides of the cabinet 2 . like this , since the tub 40 according to the second embodiment has both sides fixed to the cabinet 2 as a straight line form , the diameter of the tub 40 can be increased . accordingly , the diameter of the drum 6 arranged in the tub 40 can be more increased . fig7 is a front sectional view showing a drum type washing machine according to a third embodiment of the present invention , fig8 is a longitudinal sectional view of the drum type washing machine according to the third embodiment of the present invention , and fig9 is a rear sectional view showing the drum type washing machine according to the third embodiment of the present invention . the drum type washing machine according to the third embodiment of the present invention comprises : a cabinet 2 for forming an appearance of a washing machine ; a tub 50 formed integrally with the cabinet 2 and for storing washing water ; a drum 6 rotatably arranged in the tub 50 for washing and dehydrating laundry ; and a supporting unit positioned at the rear side of the tub 50 and arranged between the supporting plate 12 to which the driving motor 8 is fixed and the cabinet 2 for supporting the drum 6 with buffering . the tub 50 is composed of a first partition wall 52 fixed to the upper front inner wall and both sides inner wall of the cabinet 2 ; and a second partition wall 54 integrally fixed to the lower front inner wall and both sides inner wall of the cabinet 2 . the first partition wall 52 of a flat plate shape is formed at the upper side of the cabinet 2 in a state that the front side and both sides are integrally formed at the inner wall of the cabinet 2 or fixed thereto . also , the second partition wall 54 of a semi - circle shape is formed at the lower side of the cabinet 2 in a state that the front side and both sides are integrally formed at the inner wall of the cabinet 2 or fixed thereto . the supporting unit comprises : a plurality of upper supporting rods 56 connected to the upper side of the supporting plate 12 and having a predetermined length ; buffering springs 58 connected between the upper supporting rods 56 and the upper inner wall of the cabinet 2 for buffering ; a plurality of lower supporting rods 60 connected to the lower side of the supporting plate 12 and having a predetermined length ; and dampers 62 connected between the lower supporting rods 60 and the lower inner wall of the cabinet 2 for absorbing vibration . herein , the upper supporting rods 56 are bent to be connected to the upper side of the supporting plate 12 and positioned at the upper side of the first partition wall 52 , and the buffering springs 58 are connected to the end portion of the upper supporting rods 56 . also , the lower supporting rods 60 are bent to be connected to the lower side of the supporting plate 12 and positioned at the lower side of the second partition wall 54 , and the dampers 62 are connected to the end portion of the lower supporting rods 56 . in the drum type washing machine according to the present invention , a size of the drum can be maximized by fixing the tub in the cabinet , thereby increasing washing capacity of the drum without increasing a size of the cabinet . also , since the front surface of the tub is integrally formed at the inner wall of the cabinet and the gasket is installed between the rear surface of the tub and the supporting plate , a length of the drum can be increased and thus the washing capacity of the drum can be increased . as the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof , it should also be understood that the above - described embodiments are not limited by any of the details of the foregoing description , unless otherwise specified , but rather should be construed broadly within its spirit and scope as defined in the appended claims , and therefore all changes and modifications that fall within the metes and bounds of the claims , or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims .