A starter includes: a pinion gear capable of engaging with a ring gear connected to a crank shaft of an engine; an actuator for moving, in a driving state, the pinion gear to a position at which the pinion gear engages with the ring gear; and a motor for causing the pinion gear to rotate. When the engine is to be started as a result of the driver's intent to begin travel, either an engaging mode in which the pinion gear is caused to engage with the ring gear by the actuator prior to driving of the motor, or a rotation mode in which the motor is driven prior to driving of the actuator, is selected. When the engine is to be started as a result of the driver's intent to begin travel, the engaging mode is selected.