Disclosed herein is a case which protects a plurality of flexible lithium polymer unit cells, has a compact structure to reduce volume, has a simple assembly process, and minimizes heat generated during a high-power charging or discharging operation. The battery case includes a pouch support frame to support a pouch of a unit cell having the pouch and electrode terminals. A heat radiating part having the shape of a shelf is provided on a surface of the pouch support frame, and defines a space for dispersing heat generated from the pouch. A terminal support having the shape of a wall is provided on an edge of the heat radiating part, thus supporting the electrode terminals of the unit cell.