An electromagnetic switch for a starter

There is provided an electromagnetic switch for a starter which is capable of preventing a defect caused by the formation of a leakage current between the battery terminal and the motor terminal, even in the case where the electromagnetic switch is flooded with water, , On the outer surface of a cap, a membrane switch between the battery terminal and the motor terminal is provided which are arranged to be exposed outside of the switch cover; the membrane is formed such that a wall surface thereof facing a terminal of the battery terminal and the motor terminal, which is disposed above the other port, which has a protruding shape.