A battery pack includes one or more bare cells and an exterior member. Each of the bare cells has a pair of long side surfaces opposite to each other, and short side surfaces that connect the long side surfaces. The exterior member is composed of an adhesive layer provided adjacent to the bare cells while surrounding a portion of the bare cells, and a base material layer provided on the adhesive layer. In the battery pack, the adhesive layer has one or more openings therein, and the opening is provided adjacent to a portion at which the long and short side surfaces of the bare cell come in contact with each other.