Rectangular secondary battery

A square secondary battery comprising:

• a square exterior member having an opening, a bottom, a first side wall, a second side wall, a third side wall, and a fourth side wall;
• a sealing plate that seals the opening;
• and
• a plurality of wound electrode assemblies with a flat shape respectively obtained by winding a positive electrode plate and a negative electrode plate via a separator,
• the plurality of wound electrode assemblies being arranged in the square exterior member,
• wherein each of the wound electrode assemblies has a flat region formed at its center, a first bending region having a bent outer surface formed on one end side of the flat region, and a second bending region having a bent outer surface formed on the other end side of the flat region,
• a tape is attached to the outer surface of the first bending region,
• the plurality of wound electrode assemblies are arranged in the square exterior member in a direction in which their respective winding axes are perpendicular to the bottom, and
• each of the plurality of wound electrode assemblies is arranged in the square exterior member such that the respective first bending regions are positioned on the side of the first side wall.