To allow a contact member to collapse smoothly interlocked with operating lever operation.

When a contact plate 23 is positionally deviated following a contact indenter 46 during operation of an operating lever, the contact plate 23 makes contact with the outer peripheral surface of a pin 29, so that the movement of the contact plate 23 is bound. Since the outer peripheral surface of the pin 29 is positioned on the boundary 22 between a steep slope 20 and a gentle slope 21, the contact plate 23 prostrates smoothly, when the pressed point of the contact plate 23 by the contact indenter 46 passes through the boundary 22.