rate acquiring section 150 a correction value storing section 160 a correction processing section 170 and a predetermined time storing section 180 the vehicle condition detecting section 110 detects vehicle conditions the vehicle conditions refer to conditions of the battery installed in a vehicle using status of electric components installed in a vehicle vehicle situation indicating such as acceleration or deceleration of a vehicle external information of a vehicle such as traffic congestion on a traveling path to a destination set in a vehicle and atmospheric temperature remaining fuel of a vehicle etc the vehicle condition detecting section 110 comprises a battery condition detecting section 111 an electric component using status detecting section 112 a vehicle situation detecting section 113 an external environment detecting section 114 and a remaining fuel detecting section 115 for detecting various conditions of the vehicle the battery condition detecting section 111 detects the voltage of the battery 200 from the voltmeter 210 the current from the ammeter 220 and the liquid temperature from the thermometer 230 the electric component using status detecting section 112 detects the using status of the electric components installed in the vehicle for example the electric component using status detecting section 112 detects whether or not an air conditioner installed in.