A switch device of the present invention includes a cylindrical member fitted into a through hole of a wristwatch case, an operating member having an operation shaft section to be inserted into the cylindrical member and an operation head section, and a lock member fixed inside the operation head section. The cylindrical member includes engaging projections, and the lock member includes resilient support sections which have a space with respect to the inner circumferential surface of the operation head section and are resiliently deformed in a radial direction, and lock sections with which the engaging projections are resiliently engaged. Accordingly, when the operating member is pushed inward and rotated, the engaging projections resiliently deform the resilient support sections and are engaged with the lock sections. Also, only by the operating member being rotated against the regulating force of the lock section, the lock sections are disengaged from the engaging projections.