The present disclosure relates to a battery management device for balancing state of charges (SOCs) of a plurality of battery cells while maintaining a substrate temperature of a substrate to which a balancing resistor of each of a plurality of battery cells is mounted to a reference temperature or below. Since the substrate temperature is maintained at the reference temperature or below by controlling the duty cycle of a balancing switch, it is possible to prevent components included in the battery management device from being overheated and damaged due to the heat generated during the balancing process.