Battery pack exhibiting enhances structural strength

There is provided a battery pack in which a pair of ribs are formed at an inner frame to extend toward plane portions of a bare cell, so that the inner frame can be fixed at the exact position of the bare cell. In one embodiment, a battery pack includes a bare cell having a pair of first side portions opposite to each other, a pair of second side portions opposite to each other, and a pair of plane portions opposite to each other. The second side portions and the plane portions are connected to ends of the first side portions. A protection circuit module is electrically connected to the bare cell. An inner frame is provided between the bare cell and the protection circuit module. The inner frame has at least a pair of ribs opposite to each other while extending toward the plane portions of the bare cell.