PROBLEM TO BE SOLVED: To easily detach components from a case body and repair/check them easily.SOLUTION: A fitting hole 54 and an opening 22 are formed in a case body 23. A switch body is housed inside a fitting cylinder 62. An operation cap 60 is fitted to one end of the fitting cylinder 62 so as to cover the switch body. A push button switch body 50 is inserted into the fitting hole 54. A fitting groove 64 is formed on an outer peripheral surface of the fitting cylinder 62 that protrudes inside of the case body 23. A fixing wedge 51 is inserted from the opening 22 and inserted into the fitting groove 64. Inclined surfaces 53 and 68 of the fitting groove 64 and the fixing wedge 51 are brought into contact with each other, and the fitting cylinder 62 is biased toward the inside in a first direction A1. By the biasing, an end edge part 60c of the operation cap 60 is brought into contact with a locking step part 71 of the fitting hole 54 and deformed, causing the fitting hole 54 and the operation cap 60 to contact each other closely in an airtight manner. By the insertion and removal of the fixing wedge 51, the push button switch body 50 is made easily detachable from the case body 23.
