GASKET AND CYLINDRICAL BATTERY

A gasket of a cylindrical battery according to an embodiment of the present disclosure comprises a cylindrical part, and a ring part which extends from one end part of the cylindrical part in the axial direction toward an inner side thereof in the radial direction. A surface of the ring part which is opposite the cylindrical part side in the axial direction has, an approximately flat surface, A protrusion is provided on the side of the ring part which is toward the cylindrical part in the axial direction. Said protrusion: is positioned with gaps in the radial direction in relation to both the cylindrical part and an inner end of the ring part in the radial direction; and protrudes in the axial direction.