A battery pack is provided. The battery pack comprises a bare cell, a protective circuit board electrically connected to the bare cell to control the charge/discharge of the bare cell, a secondary protective device connected between the bare cell and the protective circuit board and installed on one surface of the bare cell, and an insulating member disposed on the one surface of the bare cell and having a width greater than that of the secondary protective device. Due to this construction, the insulation performance of the secondary protective device is improved and the assembly of the insulating member is facilitated.