A hybrid ECU executes a program including the steps of: setting a fan driving level F for a cooling fan, as based on a high voltage battery's temperature TB, SOC and input and output currents, and a vehicular cabin's internal temperature and background noise; detecting from a signal transmitted from a voltage sensor the voltage of an auxiliary battery serving as a power supply for the cooling fan; and setting a duty command value for the cooling fan from fan driving level F and the auxiliary battery's voltage so that the duty command value is smaller as a voltage of the auxiliary battery is higher.