A power source device for rectifying the output of an AC generator in which magneto coils are in a star-shaped connection in three phases. The device includes a control rectifier circuit configured from a first control rectifier circuit for performing full-wave rectification on three-phase AC voltages, and a second control rectifier circuit for performing full-wave rectification on AC voltages obtained between neutral and each of two-phase AC output terminals selected from the three-phase AC output terminals of the generator, as well as on AC voltage obtained between the selected two-phase AC output terminals; and a controller controlling the first and second circuits so that the output of the first circuit is supplied to the load when the rotational speed of the generator is equal/less than a set speed, and the output of the second circuit is supplied to the load when the rotational speed exceeds the set speed.