To realize certain meshing while preventing abrasion and welding by an arc.

A first contact 70 is connected via a resistor 91 (a carbon based fixed contact 71 also works as it), so that a motor rotates extremely slowly. Then, an output shaft 20 rotates. Rotation of a pinion 25 is regulated, so that the pinion 25 is pressed out axially by axial components of a splines 20a and 25a and meshes with a ring gear (not shown). When a plunger 52 moves further, a second contact 80 is made conductive. The first and second contacts are connected in parallel and the first contact 70 has the resistor, so that current from a battery fully flows through the second contact circuit and the motor fully operates to start an engine.