A sealed battery includes a can for receiving an electric generator, a shape-variable plate crimped on an opening of the can, a gasket disposed between the can and the shape-variable plate, a fixing plate disposed under the shape-variable plate, an insulating member disposed between the shape-variable plate and the fixing plate, and a projection extending from the fixing plate and welded on the shape-variable plate. The projection is provided with a mechanically weak portion which is designed to be broken at an internal pressure lower than that for separating a welding portion of the projection and the shape-variable plate.
