Battery pack of structure of improved productivity and stability

PURPOSE: A battery pack is provided to improve the safety of a battery pack, to facilitate automation and the control of supply and demand of the battery pack, to minimize cost loss in abnormal operation of the battery pack. CONSTITUTION: A battery pack(100) is built in a pack case(200) in a state where two or more battery cells are electrically connected. The battery pack comprises a protection circuit module(300) for controlling overcharging, overdischarging, and overcurrent. The pack case comprises an upper case and lower case. The protection circuit module is electrically connected in the state where it is physically isolated from battery cells.