PROBLEM TO BE SOLVED: To easily attach and detach a push button switch from a case body and easily repair and inspect the same.SOLUTION: An attaching hole 54 and an opening 22 is formed in the case body 23. A push button switch body 50 is inserted into the attaching hole 54. An attaching groove 64 is formed in an outer peripheral surface of the attaching cylinder 62 projecting inside of the case body 23. A fixing wedge 51 is inserted in the attaching groove 64. The push button switch body 50 is firmly held in the attaching hole 54 by the fixing wedge 51. An end fringe part 60c of the operation cap 60 comes into contact with an engaging step part 71 of the attaching hole 54 and deforms and brings the attaching hole 54 and the operating cap 60 into airtight close contact with each other. An engaging pawl 34a of a detaching tool 34 is inserted into a gap 55 between the fixing wedge 51 and the attaching cylinder 62 when detaching the fixing wedge 51. The fixing wedge 51 is raised by the principle of leverage and the fixing wedge 51 can be easily detached from the fixing groove 64 by slightly inclining the detaching tool 34.
