A battery charger for charging an electrically-driven vehicle by connecting the electrically-driven vehicle with an external power source, the battery charger includes an earth leakage detector operable to detect earth leakage of the battery charger; an earth leakage circuit breaker operable to switch energization from the external power source; an earth leakage confirmation relay capable of forcibly causing earth leakage in a downstream circuit of the earth leakage detector; a resistor unit connected in series with the earth leakage confirmation relay and capable of being set to any one of a plurality of leakage current values; and a controller operable to switch the earth leakage circuit breaker based on a detection result of the earth leakage detector while forcibly causing earth leakage in the downstream circuit.