Provided is a busbar capable of keeping a joint strength high at a joint between dissimilar metals. The busbar (2) joins terminals of a plurality of battery cells, the terminals each including a dissimilar metal. The busbar includes: a copper portion (2e) to be connected to a first terminal (1n) of a first battery; an aluminum portion (2f) to be connected to a second terminal (1p) of a second battery; and a joint (2x) including the copper portion bonded to the aluminum portion. The aluminum portion is placed so as not to overlap the bonding region between the first terminal and the copper portion, and has arms (2f1) extending in a direction from the second terminal to the first terminal. The joint includes the copper portion bonded to the arms, and the arms have a width such that a proximal end portion is wider than a distal end portion of the arms.