A gasket which is mountable to a mounting groove provided in one member of two members and which are opposed to each other so as to be brought into pressure contact with and pinched with respect to another member, and is made of rubber-like elastic material, said gasket comprising a body section which is inserted to said mounting groove, wherein the body section defines a width direction and has one end side and another end side in said width direction, said gasket further comprises one support protrusion provided in said one end side in said width direction of said body section which said one support protrusion in use comes into contact with a bottom portion side of said mounting groove, and further comprises a lip protrusion which is provided by two slant surfaces, a slant surface and another slant surface, wherein said lip protrusion extends from said body section to a side facing to said another member from said body section, wherein a leading end portion of said lip protrusion is positioned in an approximately center portion of said body section in the width direction of said body section, characterized in that another support protrusion in said width direction of said body section is shorter in comparison with the one support protrusion, wherein said gasket is arranged such that, in use, a gap exists between said another support protrusion at the another end side in the width direction of said body section and said bottom portion in a stage before said gasket is embedded, and said body section in use displaces in such a manner as to be inclined to said gap side around said one support protrusion as a supporting point in a stage in which said gasket is embedded, said slant surface in the side of said another support protrusion comes to a slant surface which is approximately in parallel to the center of the axis of the gasket, said slant surface arranged in the side of said another support protrusion provided with said gap is steeper in comparison with said another slant surface in said stage before said gasket is embedded. a body section which is inserted to said mounting groove, wherein the body section defines a width direction and has one end side and another end side in said width direction, said gasket further comprises one support protrusion provided in said one end side in said width direction of said body section which said one support protrusion in use comes into contact with a bottom portion side of said mounting groove, and further comprises a lip protrusion which is provided by two slant surfaces, a slant surface and another slant surface, wherein said lip protrusion extends from said body section to a side facing to said another member from said body section, wherein a leading end portion of said lip protrusion is positioned in an approximately center portion of said body section in the width direction of said body section, characterized in that another support protrusion in said width direction of said body section is shorter in comparison with the one support protrusion, wherein said gasket is arranged such that, in use, a gap exists between said another support protrusion at the another end side in the width direction of said body section and said bottom portion in a stage before said gasket is embedded, and said body section in use displaces in such a manner as to be inclined to said gap side around said one support protrusion as a supporting point in a stage in which said gasket is embedded, said slant surface in the side of said another support protrusion comes to a slant surface which is approximately in parallel to the center of the axis of the gasket, said slant surface arranged in the side of said another support protrusion provided with said gap is steeper in comparison with said another slant surface in said stage before said gasket is embedded.