An electromagnetic switch for a starter is provided. In the switch, a switch case has an open end formed and a molding cap has two terminals connected electrically to external leads and a fitting end. The fitting end is mutually fitted to the open end of the switch case. A pair of fixed contacts is disposed inside the molding cap, each fixed contact being integrally secured to each terminal. A movable contact is movably disposed to face the pair of fixed contacts. An excitation coil generates a magnetic force necessary for driving the movable contact. Further, the switch case includes a winding-up belt piece integrally formed to a circumference of the open end to extend outwardly in its axial direction. The molding cap includes a circumferential groove formed on an outer surface of the fitting end of the molding cap, the winding-up belt piece winding up the whole circumferential groove.