A battery pack includes a module. The module includes one or more cell pairs. Each of the one or more cell pairs includes a first cell and a second cell. The first cell includes an exterior package, an electrode assembly, and an electrode terminal. The electrode terminal includes a first main surface and a second main surface. The first main surface is oriented in a direction of the second cell. A sealing portion is formed at a peripheral edge of the exterior package. The sealing portion includes a first region, a second region, and a third region. The first region is formed between the first main surface and the resin layer. The second region is formed between the second main surface and the resin layer. The third region is formed between portions of the resin layer. The second region includes a fracture promoting portion.