A push-button switch may include a housing, a plunger, an operation unit, a transmission mechanism, a contact mechanism, and a biasing portion. The plunger have a first plunger and a second plunger that is disposed in series with the first plunger. The first plunger and the second plunger may be movable independently of each other. The contact mechanism may be configured to be opened/closed by movement of the second plunger.