Abstract: A thermally responsive switch comprises a housing enclosing a contact arm bearing a fixed contact and a thermally responsive snap-acting element designed to move and return with snap action depending upon the degree of switch self-generated heat or the ambient temperature. One end of the snap-acting element carries a movable contact and its other end is the supporting portion connected to a metallically elastic member mounted in the housing. To a stationary member integrated with the housing, an end support element and a central support element are respectively mounted. The end support element engages the supporting portion of the snap-acting element against the elastically urging force of the elastic member to push in one direction, while the central support element engages a middle portion of the snap-acting element to push in the opposite direction.