PURPOSE: To improve the compactness further to facilitate clutch assembly workability without generating unreasonable force of prying or the like by arranging a clutch plate holding part of a torque transmitting member, mounted to a clutch drum, between arm parts of a piston member.

CONSTITUTION: When pressure oil is supplied to an actuator 9 of a clutch drum 6, a piston member 9a of the actuator 9 is extended connecting a clutch C1. While, when pressure oil is supplied to an oil chamber 7c of an actuator 7 in the outer of the drum 6, a piston member 10 is moved in the axial direction, further its arm part 10a gives force in the axial direction to clutch plates 14a, 14b, connecting a clutch C3. Then rotation of an input shaft 5 is transmitted by the drum 6 and a pawl part 8b to a torque transmitting member 8 integrally rotating with the drum, to the clutch C3 through a holding part 8a and to a planetary gear unit and its element R2. Thus applying no unreasonable force when the piston member 10 is moved, the clutch C3 can be smoothly operated.