A bus bar has: a first joint part connected to an output terminal of the first cell; a second joint part connected to an output terminal of the second cell; and a projection that is disposed between the first joint part and the second joint part and protrudes in a stacking direction in which the cells and the bus bar are stacked. The projection has a first inclined part extending from the first joint part and has a second inclined part extending from the second joint part. The first inclined part and the second inclined part are arranged in such a manner that the first inclined part and the second inclined part are aligned with a predetermined interval W and that the predetermined interval gradually becomes wider from a first end side toward a second end side.