A vehicle identifying unit obtains an identification number of a vehicle from the vehicle. A first evaluation unit evaluates a degradation state of a power storage device based on the use history of the power storage device obtained from the vehicle, using data analyzed beforehand concerning the relation between the use history and the degradation state of the power storage device. A second evaluation unit evaluates a degradation state of the power storage device using data collected when the power storage device of the vehicle is charged from a power station or when power is fed from the vehicle to the power station. A degradation determining unit determines the degradation state of the power storage device based on the degradation states evaluated by the first and second evaluation units.