To improve startability by reducing an influence occurring due to a load during starting of an engine.

A control part 1000 turns ON a relay RyA when an engine stop is detected by an Ne sensor 153. A starter relay control part 400 turns ON the relay RyA when a starter switch is operated. The relay RyB is maintained at an OFF-state during a time set according to an engine water temperature. When the relay RyA is turned ON, a starter motor 171 is energized and while the relay RyB is in an OFF state, a motor 171 is reversed and when the relay RyB is brought into an ON-state, the motor is run normally. This constitution decides the degree of warming up according to a water temperature, shortens a crank reversing time when warming up is progressed, and lengths a crank reverse time when warming up is not progressed. Through reversing of a time set described above, a crank is positioned in a low load torque range and thereafter, the motor is run normally.