A sealed electric switch comprises a molded switch housing and a separately formed cover which fits on the switch housing wiht an annular seal member interposed between mating peripheral surfaces of the switch housing and the cover. An annular seal member is injection-molded from an elastic material on the mating peripheral surface of the switch housing between separable molding dies with the switch housing held therebetween. The annular seal member is integrally formed with an additional segment which extends in a separating direction of the molding dies and joins at its end to the annular seal member so as to reinforce it against a separation force applied thereto at the time of separating the molding dies.
