Abstract: A starter motor has an armature, a commutator and brushes slidably supported by a brush holder, and a magnet switch controls motor operation. A switch supporting member supports the magnet switch and an energization control unit accommodating a bimetal switch having a contact therein. The energization control unit opens its inner contact to shut off the current carried to a magnet switch coil when the temperature of heat transferred via switch supporting member, i.e., the heat of the coil transferred via brushes and a switch yoke, reaches a predetermined temperature, thereby stopping motor operation.