To simultaneously achieve both reduction of operating load required for clutch disengagement and reduction of shock when a clutch is connected from an idling state in a friction clutch of a motorcycle, etc.

The clutch 2 includes a clutch housing 46 having a friction plate 64, a clutch boss 48 having a clutch plate 65, a pressure plate 77, a sub clutch 100, and a power-assist mechanism 200. The power-assist mechanism 200 receives rotation force from the pressure plate 77 when clutch is disengaged and converts the rotation force into a force for moving the pressure plate 77 in the direction of separating the pressure plate 77 from a plate group 66. A cam surface 81, which supports and guides a roller weight 41, is formed on the pressure plate 77. The roller weight 41 moves outward in a radial direction by a movement amount according to the magnitude of centrifugal force and presses the pressure plate 77 toward the plate group 66 side with force according to the quantity of movement.