A battery pack includes a plurality of battery modules including a plurality of cells aligned and accommodated in a case, wherein a battery assembly in which the plurality of cells are aligned in a row is used as a unit, and the multiple ones of the battery assembly are aligned in each battery module. The battery modules are a first battery module in which the plurality of battery assemblies are aligned in parallel and second battery modules in which the plurality of battery assemblies are aligned in series, and the first battery module and the second battery modules are combined with each other to form the battery pack.