Battery module

A battery module includes a plurality of flat batteries stacked upon one another in a thickness direction. The plurality of flat batteries each have an outer cover and plate-shaped electrode terminals connected. A power generating element is sealed within the outer cover of each of the plurality of flat batteries. The electrode terminals include substantially flat plates connected to the power generating element and projecting out of the outer cover in a projecting direction. The electrode terminals of the plurality of batteries are electrically connected to each other. Each of a plurality of electrically insulating spacers receives the electrode terminals of more than one of the flat batteries and the spacers are stacked in the thickness direction of the flat batteries. At least one of the insulating spacers has an opening along a projecting direction of the electrode terminal so as to expose a portion of the electrode terminal while supporting the plurality of electrode terminals spaced from each other in the thickness direction of the flat batteries.