Provided is a battery pack. The battery pack includes: a bare cell including a bare cell main body including an electrode assembly and a sealing portion around the bare cell main body; a circuit board electrically connected to the bare cell and comprising a front surface portion opposite to the bare cell main body, wherein a chamfer portion that is inclined diagonally with respect to the front surface portion is formed at a side of the front surface portion; and a connection line extending via the chamfer portion of the circuit board. Accordingly, physical interference with a set device in which the battery pack is mounted may be avoided in the limited space of the set device, and damage to or a short circuit of the connection line which establishes an electrical connection with the set device may be prevented.