BATTERY LID

A battery lid is formed of a metal plate integrally formed with a valve and a surrounding plate portion surrounding the valve which facilitates rupturing the valve at a predetermined pressure. The valve includes a pressure receiving plate portion having a bending groove, and bendable from the bending groove by applied pressure, and a thin plate portion thinner than the thickness of the surrounding plate portion, and connects the pressure receiving plate portion to the surrounding plate portion. The thin plate portion has a rupture groove passing through extension sections on the respective lines extending from the bending groove. As the pressure receiving plate portion is deformed by the pressure applied to the valve, the extension sections are pulled more strongly than are the other sections in the valve. Therefore, when a predetermined pressure is applied, the valve is ruptured from the extension sections of the rupture groove.