To provide a push button switch capable of lowering height when in no use while maintaining operability and reliability in a push button switch used for an input device requiring thinning of a display part folding type word processor or the like.

With regard to a position of a pivot link part turnably crossing and linking each arm of two sets of frame bodies 17 and 18 forming a link member 19 whose top end bottom ends are linked with a key top 6 and a case 5, a distance up to the key top 6 is greater than that up to the case 5, thereby operation strokes of a dome body 13 can be reduced by 1/2 of operation strokes of the key top 6, the entire dimensions of the dome body 13 is reduced, and miniaturized, and the push button switch with its small height dimensions while in no use is provided while operability and reliability is maintained.