To charge it to voltage larger than battery voltage with little power loss at regeneration, in an electric motorcar power supply controller which is equipped with a large-capacity capacitor in addition to a battery, and mainly charges the capacitor at the time of regeneration, and supplies a vehicle driving motor with power from that capacitor or battery at the time excluding the time of regeneration.

At the time of regeneration, a capacitor 1 is charged directly with a regenerated currents through an exclusive wiring 12. A unidirectional converter 8 is stepped up or stepped down from the side of a capacitor 1 to the side of a battery 4, which obviates the necessity to put the capacitor charge voltage to battery voltage or under. When a regenerated current gets over a specified value, the unidirectional converter is operated to turn the amount of its excess to the charge of the battery. By doing it so, the power loss at the capacitor does not become large. In the case of supplying it from the capacitor 1, the power supply is made by stepping up or stepping down the voltage of the capacitor so that the output voltage of the unidirectional converter may amount to battery voltage or thereabouts.