Method of Manufacturing Battery Pack and Battery Pack

A method of manufacturing a battery pack including battery cells that have electrode tabs protruding from an outer surface includes stacking the battery cells and housing the battery cells in a case so that the electrode tabs protrude from slits in the case, bending the electrode tabs protruding from the slits so that the electrode tabs of adjacent battery cells are folded and overlap each other, and welding the folded and overlapping portion of the electrode tabs.