A switch for sensing a preset position of a throttle valve in an internal combustion engine, includes a stationary casing, a plunger movably disposed in the casing, and a throttle lever secured to the throttle valve so as to be moved along with the throttle valve. A first contact is supported on the casing. A second contact is supported on the plunger in such a manner as to contact the first contact according to the movement of the plunger. The throttle lever is so arranged as to be able to move the plunger and as to encounter the casing when the throttle lever moves, whereby the first and second contacts contact according to the movement of the throttle valve and the casing stops the movement of the throttle valve.