Provided is a method for charging/discharging a battery pack having an auxiliary charging/discharging device and a battery assembly in which a plurality of secondary battery cell parallel modules, each of which includes a plurality of fasecondary battery cells connected in parallel, are connected in series, the method including, when there is no abnormality in the secondary battery cells during charging/discharging, connecting the auxiliary charging/discharging device in parallel to any of the secondary battery cell parallel modules, and when there is an abnormality in any of the secondary battery cells during charging/discharging, releasing connection to the secondary battery cell at which the abnormality has arisen in the secondary battery cell parallel module including the secondary battery cell at which the abnormality has arisen, and connecting the auxiliary charging/discharging device in parallel to the secondary battery cell parallel module including the secondary battery cell at which the abnormality has arisen.