Two or more series-connected sets are arranged in a vertical direction and connected in series through an interstage wire. Each of the two or more series-connected sets includes two or more module batteries that are arranged in a horizontal direction and connected in series through an intrastage wire. The main pole feedthrough part penetrates through a side wall of the container. The main pole terminal is disposed outside the case. An insulator of the main pole supporter insulates a first coupling part and a second coupling part from each other. The first coupling part is coupled to the base, and the second coupling part is coupled to the main pole terminal. The two or more cells are housed in an accommodation space and charged and discharged via the main pole.