A clutch mechanism includes rotation operating unit for rotating a second rotational member integrally with a first rotational member, the rotation operating unit includes a collar member installed near the second end of the operating spring, and at least one braking member rotatably disposed generating biasing force containing an element in a radial direction relative to a circumferential slidable contact surface of the collar member. The braking member includes an engaging portion configured to engage the second edge of the operating spring therewith.