A battery pack includes a battery including at least one battery cell, a cell balancing device configured to balance a voltage of the at least one battery cell, a switch unit including a charging switch and a discharging switch arranged on a high current path through which a charging current and a discharging current flow, and a battery management unit configured to monitor a voltage and a current of the battery, to control the cell balancing device, and to control charging and discharging operations of the battery, wherein when a state of the battery during charging with a constant current satisfies a preset swelling condition, the battery management unit is configured to operate the cell balancing device for a preset discharging time to make the battery self-discharge, when the present discharging time passes, the battery management unit is configured to pause the battery from self-discharging for a preset pausing time, and when the preset pausing time passes, the battery management unit is configured to charge the battery.