The invention is provided with an automatic transmission (2) having a clutch (32), and a braking device (6) for maintaining braking power when the engine (1) is stopped. The invention is provided with an engine control unit (11) for automatically stopping and restarting the engine (1), and a release control unit (14) for releasing the maintaining of the braking power during restarting. During restarting of the engine, when the accelerator is off until the clutch (32) reaches a prescribed state of engagement, the release control unit (14) releases the maintaining of the braking power when the clutch (32) is in the prescribed state of engagement, and when the accelerator is on until the clutch (32) reaches the prescribed state of engagement, the release control unit (14) releases the maintaining of the braking power when the clutch (32) is in an engagement state weaker than the prescribed engagement state.