friction engaging elements and an inner surface of the clutch case 16 and a spring 41 is disposed between the piston 18 and the clutch case 16 the spring 41 is a coil spring having predetermined elasticity but may be a spring of other type the piston 18 is always biased toward a direction along which the friction plates 12 and the separator plates 13 are frictionally engaged or joined together by a mechanical urging force of the spring 41 in order to release an engaging condition between the friction plates 12 and the separator plates 13 a hydraulic mechanism described later is used the starting clutch 10 further includes the multi plate clutch 11 a housing 20 covering an outer periphery of the multi plate clutch 11 and a damper 17 acting as a shock damping mechanism and disposed between the clutch case 16 and the housing 20 incidentally the damper 17 is provided on an inner wall of the housing 20 and is constituted by a retainer plate 22 for holding a spring 21 and a pawl 23 engaging the spring 21 the retainer plate 22 is secured to the housing 20 by a rivet 37 the housing 20 covers the multi plate clutch 11 the piston 18 and a cylinder portion which will be described later a thrust washer 24 is disposed between the clutch case 16 and the housing 20 a needle bearing may be used in place of the thrust washer 24 a driven rotary member 3 is fitted into the clutch case 16 the driven rotary member 3 is rotatably supported by a fixed member 2 through a bearing 6 the fixed member 2 is supported by an output shaft 1 through a seal bearing.