The pressing member is configured to move to an off-position and an on-position. When the pressing member is located at the off-position, the first contact and the second contact come into a non-contact state. When the pressing member is located at the on-position, the first contact and the second contact come into a contact state by press of the pressing member against the contact piece. The actuator moves the pressing member from the off-position to the on-position via an overshoot position located beyond the on-position. The contact piece includes a body, and a low rigidity portion having rigidity lower than rigidity of the body. The pressing member presses the low rigidity portion.