A prismatic battery module includes a prismatic battery case (3) having a plurality of prismatic cell cases (4) connected to one another through separation walls (5), a planar electroconductive connector (16, 17) forming part of the separation wall (5) between the cell cases (4), an electrode plate group (8) arranged in each cell case (4), and an electrolyte placed in each cell case (4). Lead portions (9a, 9b) of positive electrode plates and negative electrode plates of the electrode plate group (8) are directly connected to the electroconductive connector (16, 17). The prismatic battery module requires fewer connection points and provides shorter electrical communication paths, thereby reducing internal resistance.