According to an embodiment of the present invention, a battery pack is provided with, for instance, a housing, a plurality of battery cells, and a first connector. The housing has a first outer wall section, and a protruding section, which is provided on the first outer wall section, and which is protruding to the outer side of the first outer wall section. The battery cells have electrode terminals, respectively, and are housed in the housing. The first connector is provided in the protruding section, and is electrically connected to the electrode terminals.