A battery module has stacked therein a plurality of flat cells each formed by sealing a power generating element with a package member and deriving to the exterior electrode tabs from the package member and has the electrode tabs of the flat cells connected electrically. The battery module includes electrically insulated spacers adapted to nip the electrode tab from the opposite surface sides of the electrode tab along the stacking direction of the plurality of flat cells. The paired spacers nipping the electrode tab include an engaging member adapted to fasten the electrode tab by being passed through the electrode tab along the stacking direction.