Abstract: An outer casing of a non-aqueous electrolyte battery is capable of being mass-produced as well as thin and resistant to damage. The outer casing 4 comprises a casing body 4a and a cover 4b. After being internally packaged, a non-aqueous electrolyte battery 2, e.g. a lithium-ion polymer secondary battery, is sandwiched between the casing body 4a and the cover 4b, which are then joined together integrally. The cover 4b is formed from a film-shaped sheet material 4c of a synthetic resin to make the outer casing 4 thin. The casing body 4a and the cover 4b have a casing body outer peripheral frame 9 and a cover outer peripheral frame 10, respectively, formed by injection molding. Joint portions of the casing body 4a and the cover 4b have stepped portions 9a and 10a, respectively. The stepped portions ensure the mechanical strength against shock and impact. With this structure, the outer casing 4 is resistant to damage.