To provide a clutch device with two friction clutches arranged back to back, allowing the free setting of the number of clutch discs corresponding to specifications.

The clutch device 60 comprises two first and second bypass clutches 41, 42 as friction clutches arranged neighboring each other for thrusting the clutch discs 44 to generate transmitting torque, wherein a clutch drum 61 to be used as a drum member in common with both bypass clutches 41, 42 is caulked and fixed to the outer periphery of a partition wall 62 isolating both bypass clutches 41, 42 from each other. Both bypass clutches 41, 42 each have a piston 65 for thrusting the clutch discs 44 and both pistons 65 are arranged back to back on the partition wall 62. The caulked position of the clutch drum 61 is shifted to the axial direction to permit the length of the drum to be properly allocated between both bypass clutches 41, 42 and the free setting of the number of the clutch discs 44.