A waterproof push button switch does not need to be covered with a resin to a height at which a divided connected portion of a case for the switch is hidden by the resin in a height direction and the divided connected portion may be waterproofed. A gap (55, 57) is formed between a peripheral wall portion 7b of a base case 7 and a second cylindrical wall portion 9b of a cover case 9, and between an opposite surface 41 of the cover case 9 and a waterproofing seal member 11. The gap (55, 57) extends from an opening portion of the base case fitting chamber 37 to an annular watertight seal portion 51 to completely surround a periphery of the watertight seal portion 51. The thickness of the gap portion 55 is determined so that the resin entered into the gap portion 55 from an opening portion 37a of the base case fitting chamber 37 reaches the watertight seal portion 51 by surface tension.