PURPOSE: To provide very quick and sure clutch-engagement between a clutch shoe and a clutch drum, with simple constitution.

CONSTITUTION: In a centrifugal clutch 1, when a boss 5 starts rotation, each clutch shoe 6 also rotates via a cam roller 7, linking with the rotation of the boss 5. Each clutch shoe 6 moves toward an inner peripheral surface 3 of the drum, owing to the centrifugal force. As a result, the cam roller 7 erects, with its longitudinal direction oriented toward the drum-diameter-direction, within a gap between a recessed groove parts 17 and 18. Meanwhile, when each lining 8 touches and slides on the inner peripheral surface 3 of the drum, the cam roller 7 erects further toward the drum-diameter-direction because of the movement of each clutch shoe 6 in the opposite direction of rotation due to frictional force of the contact/sliding. Thus, the each lining 8 is further pushed/pressed against the inner peripheral surface 3 of the drum, so that the clutch shoe 6 is integrally clutch-engaged with a clutch drum 2. As a result, unnecessary slip and hunting during the period from the start of the contact/sliding to the clutch engagement can be eliminated.