A system is installed in a vehicle having an internal combustion engine, a transmission, and a clutch. The system restarts, according to at least one engine restart condition is met, the internal combustion engine that has been automatically controlled for stop thereof. The system includes a restart-condition determiner configured to determine that, as the at least one engine restart condition, an operation of the clutch is started by a driver of the vehicle for shifting the second state to the first state. The system includes a state detector configured to detect an operated state of the clutch during the clutch is shifted from a disengagement state to an engagement state. The system includes a restart controller configured to determine whether to enable or disable the restart of the internal combustion engine according to the operated state of the clutch detected by the state detector.