Battery voltage controller

A battery voltage controller (1) includes: a plurality of voltage detection circuits (D1 to DN); a voltage controller (M); and a charge transfer circuit (E). The voltage detection circuits respectively include a plurality of voltage detection capacitors. Each of the voltage detection circuits is configured to output a voltage between terminals of one of the voltage detection capacitors after the voltage detection capacitors are respectively charged by a plurality of battery cells. The voltage controller (M) is configured to obtain output voltages of the voltage detection circuits as results of voltage detection for the battery cells, and perform voltage balance control of the battery cells based on the results of the voltage detection. The charge transfer circuit is configured to transfer electric charge from one of the voltage detection capacitors to a charge transfer capacitor according to control by the voltage controller, and transfer electric charge from the charge transfer capacitor to another one of the voltage detection capacitors.