In a battery cooling system that cools a battery by using conditioned air (inside air of a passenger compartment) of a vehicle air conditioner, a battery control unit controls a battery blower to increase an air amount supplied to the battery when a predetermined condition is satisfied. In contrast, an air-conditioning control unit decreases a compression capacity of a compression device after an air amount supplied to the battery is increased to a predetermined amount by the battery control unit. For example, the air-conditioning control unit decreases the compression capacity of the compression device after a predetermined time passes after the air amount supplied to the battery is increased to the predetermined amount. Accordingly, the temperature inside the passenger compartment and the compression device can be stably controlled.