Abstract: Provided is a gasket capable of reducing the risk of water leakage from a sealing member for use to join a ceramic member. The gasket is made of elastic material and usable for joining two members which form a flow passage for liquid, and at least one of which is a ceramic member. The gasket includes: a base having a loop shape; a protrusion standing on the base, extending along the loop shape, and protruding toward one of the members; and a retainer formed on an inner periphery of the base and protruding from the inner periphery in an inward direction with respect to the loop shape.