A switch structure comprising an actuator reciprocally movably mounted on a casing so as to control a contact structure, a cardio-shaped grooved cam provided with the actuator, a wire spring secured at one end to the casing and disposed at other free end in the grooved cam, a locker structure which alternatively holds the actuator at a return position or at an operative position by selectively engaging the free end of the wire spring with the first or second engagement portions each provided with the grooved cam, and an electromagnetic solenoid which releases the free end of the wire spring from the second engagement portion.