A push-button switch provided with a hollow push button, a case supporting it, and a switching mechanism having a first contact disposed within the case and a second contact disposed opposite to the first contact, with one of its ends being inserted into a hole of the push button. Within a hole formed in an inserted section of the switching mechanism, a slide block is provided slidably in a direction crossing the direction in which the push button is pushed. A slope capable of engaging with a slope of the hole of the push button is formed on the slide block. A coil spring (return spring) for energizing a shaft of the switching mechanism so as to abut the push button is provided on the bottom of the case. This configuration enables the push button to take up a first OFF state, an ON state and a second OFF state in order of depression.