A push-on switch which comprises a movable contact plate formed by a metal plate spring, and in which said movable contact plate Is fixed onto a circuit board by an adhesive tape (9, 19) that is bonded from a side of an upper face of said movable contact plate, said movable contact plate having: an annular peripheral plate portion; a center plate portion which is upward inflatingly curved; and connecting plate portions (4, 4) which connect said peripheral plate portion and said center plate portion together, said connecting plate portions (4, 4) being inverted by an operation of depressing said center plate portion to a downward inclined state to make contact with first stationary contacts (11, 11) on said circuit board, said center plate portion being then inverted to a downward inflated state to make contact with a second stationary contact on said circuit board, and a spacer which is placed around said movable contact plate on said circuit board, wherein said spacer is an annular spacer formed so as to surround the periphery of the movable contact plate, and the upperface of the spacer forms a continuous tape-sticking face, said tape sticking face being lower in level than a top of said center plate portion and higher than said peripheral plate portion, wherein a covered space inside the spacer defined by the inner peripheral wall of the spacer, the circuit board, and the adhesive tape (9, 19) is formed inside the spacer, wherein a covered space outside the spacer defined by the outer peripheral wall of the spacer, the circuit board, and the adhesive tape which is obliquely stretched between the tape-sticking face of the spacer and the circuit board is formed outside the spacer, wherein an air passage through which said covered space inside the spacer is communicatingly connected to said covered space outside the spacer is formed between the tape-sticking face of the upper face of the spacer and the adhesive tape sticking to the face, by a groove formed in said spacer, and wherein said push-on switch further comprises air escape means formed in the adhesive tape (9, 19) in the vicinity of an opening of the air passage on the side of the covered space outside the spacer, wherein said covered space outside the spacer communicates with a space outside said adhesive tape (9, 19) through said air escape means. an annular peripheral plate portion; a center plate portion which is upward inflatingly curved; and connecting plate portions (4, 4) which connect said peripheral plate portion and said center plate portion together, said connecting plate portions (4, 4) being inverted by an operation of depressing said center plate portion to a downward inclined state to make contact with first stationary contacts (11, 11) on said circuit board, said center plate portion being then inverted to a downward inflated state to make contact with a second stationary contact on said circuit board, and a spacer which is placed around said movable contact plate on said circuit board, wherein said spacer is an annular spacer formed so as to surround the periphery of the movable contact plate, and the upperface of the spacer forms a continuous tape-sticking face, said tape sticking face being lower in level than a top of said center plate portion and higher than said peripheral plate portion, wherein a covered space inside the spacer defined by the inner peripheral wall of the spacer, the circuit board, and the adhesive tape (9, 19) is formed inside the spacer, wherein a covered space outside the spacer defined by the outer peripheral wall of the spacer, the circuit board, and the adhesive tape which is obliquely stretched between the tape-sticking face of the spacer and the circuit board is formed outside the spacer, wherein an air passage through which said covered space inside the spacer is communicatingly connected to said covered space outside the spacer is formed between the tape-sticking face of the upper face of the spacer and the adhesive tape sticking to the face, by a groove formed in said spacer, and wherein said push-on switch further comprises air escape means formed in the adhesive tape (9, 19) in the vicinity of an opening of the air passage on the side of the covered space outside the spacer, wherein said covered space outside the spacer communicates with a space outside said adhesive tape (9, 19) through said air escape means.