Disclosed is a battery module including a base plate on which unit modules, each with two or more secondary batteries therein, are stacked in a vertically erected state, a pair of end plates disposed in tight contact with outer surfaces of outermost unit modules while bottoms of the end plates are fixed to the base plate, and supporting bars connected between opposite sides of upper or side parts of the end plates so as to support the end plates, wherein each of the end plates includes a main body contacting a corresponding one of the unit modules, and a top wall, a bottom wall, and a pair of side walls protruding outward from the perimeter of the main body, the thickness of each of the side walls being increased from the top to the bottom wall, thereby dispersing pressure (bending load) from the unit modules and the supporting bars.