A bus bar holding structure includes a bus bar, an insulating resin-made wire distribution body holding the bus bar. The bus bar electrically connects together an adjacent terminals of a plurality of unit cells each having positive pole and negative pole electrode terminals. The bus bar includes a plate-shaped main body and a wire connecting part extended from the plate-shaped main body and connected to an end of a wire. The plate-shaped main body includes a fold-back part and a plurality of plate parts separated from each other at the fold-back part and folded back at the fold-back part so as to be superimposed with each other. The plate-shaped main body and the wire connecting part are formed integrally.