A forcibly moving mechanism is provided with a first pressing body for applying a pressing force to a latch body located at a standby position, said pressing force pressing the latch body toward a retracted position thereof. A striker body is captured at a predetermined position by the latch body which is being retained at the standby position, and the capturing of the striker body releases the latch body from the retention. As a result, the latch body moves to the retracted position, and this moves a movable body to a movement end position. A braking mechanism is provided with a contact section for making contact with the latch body which constitutes the forcibly moving mechanism. The braking mechanism is configured to apply resistance to the backward movement of the contact section caused by the movement of the latch body to the retracted position, and the braking mechanism is provided with a second pressing body for pressing the contact section in the forward movement direction.