STACKED SECONDARY BATTERY

This stacked secondary battery has: an electrode body (11) in which at least one positive plate (14) and at least one negative plate (17) are stacked, with a multilayered separator (20) interposed therebetween, said separator including two porous layers that are formed from different materials; and an outer packaging case that houses an insulating holder and an electrolyte together, said insulating holder housing the electrode body and being formed by folding and overlapping a sheet that comprises an insulating material. The outer packaging case has a bottom surface, a plurality of side walls that are provided standing upright from the bottom surface, and an opening that is opposite from the bottom surface and is surrounded by the plurality of side walls. In at least one separator, a section that is exposed from end surfaces of active material mixture layers and metal foil-comprising core bodies of the positive plate and the negative plate is in contact with the vicinity of a bottom line P of a valley section