A control device for a vehicle includes: a motor generator mechanically connected to an output shaft of an engine; a main battery electrically connected to the motor generator; a sub battery electrically connected to an electric load of the vehicle; and a relay adapted to switch whether the batteries are to be electrically connected or not by turning the relay on or off. The relay is turned off during a powering operation of the motor generator, and the relay is turned on during a regenerative operation of the motor generator. It is determined that the relay is off-fixed in a case where a voltage of the second battery is a predetermined voltage or lower or a charge current of the second battery is a predetermined current or smaller in a state that a command to turn on the relay is outputted during the regenerative operation of the motor generator.