A bus bar includes a plurality of fastening holes in which a plurality of electrodes of a single cell is fastened with a nut, and a plurality of projections formed between the fastening holes and projecting in a direction away from the single cell. A case includes a bus bar hosing portion in which the bus bar is housed, and a support portion disposed in the projection of the bus bar housed in the bus bar housing portion and abutting against a back surface of the projection to support the bus bar. The support portion has a width smaller than an interval between inner side surfaces of side plate portions of the projection.