To prevent a clutch mechanism from being locked due to a bite in the case of employing a roller when a rotational power transmission device is provided with a clutch mechanism 16 for locking rotation on the reverse side though transmitting rotation from a drive side rotor 18 to a driven side rotor 19.

When a drive side rotor 18 rotates, a driven side rotor 19 and operation receiver 23 are integrally pivoted. When the driven side rotor 19 rotates, on the other hand, an actuator 20 enters between a pair of operation receivers 23 to move it in an axial core direction, and is abutted on a rotation receiver 22 of a fixed side to lock the rotation.