An electromagnetic switch unit comprises a solenoid device that pushes out a pinion gear to a ring gear side of an engine, and an electromagnetic switch that opens and closes a main point of contact of a motor circuit. The solenoid device and the electromagnetic switch are arranged in series in an axial direction, while a magnetic plate that forms a part of magnetic circuit between a first coil used for the solenoid device and a second coil used for the electromagnetic switch is shared by the solenoid device and the electromagnetic switch.