Disclosed herein is a middle- or large-sized battery module comprising a plurality of stacked unit cells, each unit module including two or more plate-shaped battery cells electrically connected with each other, each battery cell having electrode terminals formed at opposite sides thereof. The battery module is manufactured by connecting electrode terminals of a pair of unit modules by welding, mounting a sensing unit, including a sensing member, to the welding part and bending the welding part such that the unit modules are stacked, and repeatedly performing the above processes until all the unit cells are stacked.