Rectangular secondary battery

The purpose of the present invention is to provide a higher capacity rectangular secondary battery. This rectangular secondary battery (100) has: flat wound electrode groups (3) having a foil laminated section wherein foil exposure sections (34b, 32b) are laminated on both sides in the winding axis direction; a battery case (1) wherein a plurality of wound electrode groups (3) are housed in parallel; collector plates (200, 210) joined to the foil laminated sections inside the battery case (1); and external terminals (14, 12) connected to the collector plates (200, 210) and exposed to the outside of the battery case (1). The rectangular secondary battery is characterized by: at least two of the wound electrode groups (3) having joined-side laminated sections (34b-1, 32b-1) and non-joined-side laminated sections (34b-2, 32b-2) that split the foil laminated section into two in the thickness direction; and the joined-side laminated sections (34b-1, 32b-1) being bundled and joined to the collector plates (200, 210