A battery pack includes: a battery cell including first and second surfaces arranged at opposite sides and at which first and second electrodes are respectively located, and a side surface connecting the first and second surfaces to each other; a first circuit board arranged on the first surface and connected to the first electrode; a second circuit board arranged on the second surface; a first flexible line extending from a first side of the first circuit board to the second circuit board while surrounding a portion of the side surface of the battery cell; and a second flexible line extending from a second side of the first circuit board to the second surface of the battery cell while surrounding another portion of the side surface of the battery cell and connected to the second electrode.