A charging system comprises: at least one charging unit for supplying power for charging a battery mounted on a vehicle to the power receiving unit of the vehicle; a power supplying unit for supplying power supplied from the outside to the charging unit; a charging control unit for instructing the charging unit about a current instruction value based on a setting value of the power to be supplied by the charging unit; a current measuring unit for measuring the value of charging current actually flowing through the power receiving unit of the vehicle by the power supplied from the power supplying unit; and a determination unit for determining, based on the measurement result of the current measuring unit, whether the power receiving unit of the vehicle can follow a change of the current instruction value or not. Based on valid charging current characteristics fallen into a predetermined error range during a predetermined valid measurement period, the determination unit determines whether the power receiving unit of the vehicle can follow a change of the current instruction value or not.