Rectangular battery with wound electrode assembly

A square shaped battery includes: an electrode plate group including a belt-like positive electrode plate, a belt-like negative electrode plate, and a belt-like separator, the belt-like positive electrode plate, the belt-like negative electrode plate, and the belt-like separator being laminated and rolled up to form the electrode plate group; and a pair of power collectors disposed on sides of the electrode plate group for collecting electric power from the electrode plate group.