There is provided a battery assembly wherein assembly can be facilitated by reducing the number of components to be assembled, by integrally fixing resin plates (52, 62) on the inside of metal plates (51, 61) of end plates (5, 6). A laminated battery body (3) is constituted by adjacently arranging battery holders (2) made of resin forming cooling passages (4) between a plurality of batteries (1) and holding such batteries (1) on both sides between other batteries (1). The metal plates (51, 61) and resin plates (52, 62) that are integrally fixed on the inside of these metal plates are provided on the outside of the batteries (1) at both ends of the laminated battery body (3). Thus, the batteries (1) are held by the resin plates (52, 62), and the end plates (5, 6) are respectively arranged to form the cooling passages (4) between these batteries (1) and the metal plates (51, 61). The laminated battery body (3) is fixed in a clamped manner by fixing means clamping these end plates (5, 6).