A battery pack including a bare cell, the bare cell including a first surface, a second surface, a pair of short side surfaces, and a pair of long side surfaces; a circuit module on the first surface of the bare cell, the circuit module being electrically connected to the bare cell; and a frame covering a portion of the bare cell including the circuit module thereon, wherein the frame has a protrusion part at interior portions of side surfaces thereof, the protrusion part being coupled to the short side surfaces of the bare cell.