The battery is sealed by a sealing member including a safety valve for exhausting the gas generated in the battery to the outside of the battery when the pressure in the battery is increased. A part of the sealing member is formed of a member having a melting point lower than that of high-temperature gas generated in the abnormal time and having a ratio of an area of an opening of the battery case to an area of a gas exhaust hole is 3.0×10−5 or more and 9.1×10−3 or less.