When a battery of an electric vehicle charged with an external power source (AC 100 V), the electric vehicle and the external power source are connected with each other by the intermediary of a charging cable. Upon this charging, it is determined whether or not an input voltage from the external power source is 95 V or more. When the input voltage is less than 95 V, that is, a decline of the voltage in the charging cable is large, since a wiring resistance in the charging cable possibly increases, an upper limit of an output power to the battery is reduced. Consequently, the electric power delivered from the external power source can be limited, and thereby excessive heat generation is inhibited and safety is ensured. Furthermore, since the output power is caused to be limited when the wiring resistance possibly increases, the battery can be charged continuously.