An example battery charging circuit includes a rectifier circuit for rectifying a three-phase AC voltage outputted from an electric power generator and generating a charge voltage for charging a battery. A voltage detection circuit detects that the voltage of the battery exceeds a predetermined voltage. A switching circuit, in an off-state, charges the battery through the rectifying circuit and, in an on-state, short-circuits the electric power generator through the rectifier circuit. A switch control circuit brings the switching circuit into the on-state, when it is detected by the voltage detection circuit that the voltage of the battery exceeds the predetermined voltage. A control circuit allows the switch control circuit to subsequently perform a control for bringing the switching circuit into the off-state.