Disclosed is a battery charge balancing device which includes: a charge-measuring unit that measures charge of a plurality of batteries storing power through a plurality of power converters connected with a plurality of input power sources; a mode-conversion parameter calculating unit that calculates mode conversion parameters for determining mode conversion such that the power converters operate in a power conversion mode for converting power or in a balancing mode for balancing charge between the batteries; and a control unit that controls power transmission path of the power converters by switching a plurality of switches connected between the power converters and the batteries in accordance with the calculated mode conversion parameters.