A pouch exterior material that enables an electrode assembly to be easily mounted on an accommodating portion at a proper position, having an integrated shape and including an inserting portion provided at a center of the pouch exterior material and having a width equal to a thickness of the electrode assembly, accommodating portions provided symmetrically at two sides of the inserting portion and gradually deepening from a portion corresponding to a width center of the electrode assembly towards a portion corresponding to an edge of the electrode assembly, and a triangular stepped portion provided at two ends of the inserting portion and having a depth gradually decreasing towards an end.