To provide a small actuator.

A torque limiter device has: a motor side plate 53 rotating together with an output shaft 11a of a motor 11, and on which unevenness is formed; a spindle side plate 59 rotating together with a spindle 13, provided coaxially with a rotation axis of a motor side plate 53, and on which unevenness is formed that can be engaged/disengaged with the unevenness of the motor side plate 53 by relatively moving to the motor side plate 53 in the rotation axial direction; an energization member 61 performing energization in a direction where the unevenness of the motor side plate 53 and that of the spindle side plate 59 are engaged with each other. The unevenness of the motor side plate 53 and that of the spindle side plate 59 have inclined planes where a component force is generated that makes the motor side plate 53 and the spindle side plate 59 separate from each other along the rotation axis when the motor side plate 53 and the spindle side plate 59 are about to rotate in the engagement.