A battery pack is disclosed. The battery pack includes at least two battery cells to provide a high capacity battery pack. The battery pack includes a single PCM assembly controlling at least two battery cells to decrease inferiority due to overcharge and overdischarge. Since a connector tab electrically connecting at least two battery cells to a single PCM assembly is provided, contacts are not separated during the swelling of the battery cells to prevent contact inferiority. A top case and a bottom case are provided to be coupled with at least two battery cells to maintain a secure coupling between the at least two battery cells.