To solve the problem where an operator could not be given a sense of operation, when switching from a off-operation to a on-operation as well as when switching from on-operation to off-operation.

When a plunger 2 is pressed in, so that a spring hooking part 52 of mobile members 45 and 46 moves from spring hooking parts 51 and 60 of a contact-point operation member 47 in the direction of pressing-in the plunger 2, a first sense of operation is provided which arises through a snap action of first and a second sense springs 43 and 44. A further pressing-in of the plunger 2 enables the mobile members 45 and 46 to be brought into contact with a case 1, and the end side of the mobile members 45 and 46 come off a first hooking recessed part 37 of the plunger 2 for hooking with a second hooking recessed part 38, thus making it disengageable. The first and second sense springs 43 and 44 perform the snap action, providing a second sense of operation.