A battery pack is disclosed. In one aspect, the battery pack includes first and second cell groups each including one or more cells, a circuit board electrically connected to the first and second cell groups and a connector provided in the circuit board and including a plurality of connector terminals. The connector terminals include first and second connector terminals respectively electrically connected to first and second electrodes of the first cell group. The connector terminals include first and second connector terminals respectively electrically connected to first and second electrodes of the second cell group. The first and third connector terminals are detachably in contact with each other, wherein the second and fourth connector terminals are detachably in contact with each other. According to some embodiments, it is possible to simply physically release a parallel connection of a plurality of cells or a plurality of cell groups.