PURPOSE: To restrict or stop the rotation of a rotary arm by locating a position where the peripheral surface of a roller makes simultaneously contact with the peripheral surface of a braking part and an opposing surface of a base member in an operating and non-operating condition of an actuator, in a gap between the peripheral surface of the braking part and the base member.

CONSTITUTION: A gap for passing an arm member 4 is defined between a base member 6 and an attaching planar surface 3a for the rotary arm 3. A position where the peripheral surface of a roller 4f makes contact with the peripheral surface of a braking part 2 and an opposing surface of a base member 6, simultaneously, in an operating or non-operating condition of an actuator 8, exists in the gap. With this arrangement, the arm member 4 is turned about a fulcrum 4d as a center by the urging force of a resilient member 5 during in the non- operating condition of the actuator 8 so that the peripheral surface of the roller 4f makes contact with the peripheral wall of the braking part 2 and the opposing surface of the base member 6, simultaneously. Accordingly, it is possible to inhibit counterclockwise rotation.