A tilt switch comprises an insulating housing, a cover covering the opening of the housing, three terminals fixed at the bottom of the housing and an electrically conductive ball movably received in the housing to on/off the switch by contacting/leaving said terminals. Three terminals are located at each vertex position of a triangle such that one terminal having a polarity opposite to the other two terminals and a protruding length longer than those of the other two terminals, allowing elevation difference to exist between them.