A switch device has an operating unit, a circuit board having a contact unit that is switched according to the operation of the operating unit, a case having the operating unit at an upper section thereof, an opening at a lower section thereof, and the circuit board inside thereof, and a cover that is fitted to the opening of the case to close the opening. A thin hinge and a flange continuous to the hinge are formed integrally with the case along a side wall at a lower end of the side wall of the case. The flange is folded and bent on the hinge, so that a clearance defined between the case and the cover is covered with the flange.