An arrangement in which a cooling air inlet provided at the front end of a battery case of an electric automobile is connected to a heat exchange unit of a vehicle-mounted air conditioner via a blower duct, cooling air issuing from the vehicle-mounted air conditioner is supplied from the blower duct to the interior of the battery case so as to cool the battery, and cooling air having an increased temperature is then discharged outside the battery case by means of an exhaust fan is known from Patent Document 1 below.