When an operation knob 10 formed of silicone rubber is pushed laterally, a stem 7 tilts with a contact portion (i) as a fulcrum, a push button portion 6b is pushed, and a contact point in a switch mechanism portion 6a operates to turn on a switch circuit. Even if, by a large operating force F3 being applied, the operation knob 10 is extended and the inner surface portion 15, which is a ceiling surface of an internal space 13 of the operation knob 10, rides on an upper end portion 7c, a reinforcing surface 19 provided on the inner surface portion 15 slides on the upper end portion 7c, and the operation knob 10 returns to the initial shape.