A battery charging apparatus includes a plurality of input terminals which are connected to respective phases of a three-phase AC dynamo, and a rectifying circuit including a plurality of rectifying elements and a plurality of switching elements. A switching element control unit and pulse generation unit are provided, for controlling the turning on/off of the switching elements, and for generating a pulse signal, respectively. The switching element control unit is configured to control the plurality of switching elements, and includes a potential difference detection unit configured to detect potential differences between potentials of input terminals, and a specifying unit configured to determine a phase order of AC outputs which are input to the input terminals.