Gasket

A gasket in an annular shape to seal a gap between a first member in which an annular groove is formed and a second member to be overlaid on the first member to close an opening of the groove, the gasket comprising:

• a body portion in an annular shape having a basal surface to contact a bottom surface of the groove and a top surface to contact the second member and extending over an entire circumferential direction of the gasket;
• a first protrusion pair protruding from the body portion respectively toward both side surfaces in a radial direction of the groove and extending over the entire circumferential direction;
• and
• one or more second protrusion pairs protruding from the first protrusion pair respectively toward both the side surfaces of the groove,
• wherein:
• respective protrusions of the second protrusion pair are disposed at a same position in the circumferential direction, and tip ends of the respective protrusions are formed in a planar shape to be along the side surfaces of the groove, and
• a first gasket width from a tip end of one protrusion of the first protrusion pair to a tip end of another protrusion is smaller than a groove width between both the side surfaces of the groove, and a second gasket width from a tip end of one protrusion of the second protrusion pair to a tip end of another protrusion is larger than the groove width,
• wherein a recessed part recessed to a body portion side and extending over the entire circumferential direction of the gasket is formed at the tip end of at least one protrusion of the first protrusion pair, and
• wherein the recessed part is formed on a central portion of the protrusion of the first protrusion pair in a cross-section taken along the height direction of the gasket.