Abstract: There is provided a sealing structure including a body portion having an outer surface at which the body portion is kept in contact with an opponent part, the body being formed with a bore therethrough, the body portion being formed at the outer surface thereof with at least one annular projection or recess designed to be swingable in a direction in which the bore extends. Since the annular projection or recess is designed to be swingable, when the body portion is connected to an opponent part through the outer surface thereof, the outer surface can be deformed, resulting in ensuring quite high sealing between the body portion and the opponent part.