NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY

A decrease in energy density of a battery is suppressed, and the occurrence of internal short circuit between a positive plate and a negative plate located at the innermost circumference of a curved portion of a flat electrode assembly, where the curvature of the curved portion is greatest, is suppressed. In a nonaqueous electrolyte secondary battery including a flat wound electrode assembly (14), the electrode assembly (14) has a pair of curved portions (20A, 20B) located at either end and a flat portion (21) located between the pair of curved portions. In at least one of the curved portions, at least two layers of a second electrode plate are disposed on an inner side of a curved portion of a first electrode plate located at an innermost circumference.