A control unit includes: an input portion that receives the positional information of a vehicle; a calculation unit that generates a control signal for controlling an electromagnetic relay; and an output portion that outputs the control signal to the electromagnetic relay. The calculation unit determines whether a location region of the electromagnetic relay is a relay-freeze region, the location region being identified by the positional information of the vehicle, and, when the location region of the electromagnetic relay is a relay-freeze region, performs a freeze inhibiting process for preventing the electromagnetic relay from being frozen or defrosting the electromagnetic relay by opening and closing the electromagnetic relay and causing the electromagnetic relay to vibrate.