According to one embodiment, a battery unit includes a first cell unit, a second cell unit and a third cell unit arranged adjacent to the first cell unit, respectively. Each cell unit includes a plurality of secondary battery cells, and the respective secondary battery cells are formed of a main body of a substantially rectangular solid shape and a pair of first and second electrodes of different polarities each other pulled out from one end of the main body. A first bus bar connects the first electrodes of the first cell unit and the second electrodes of the second cell unit in a first line, and a second bus bar connects the second electrodes of the first cell unit and the first electrodes of the third cell unit in a second line.