PURPOSE: To easily mount an O ring, by providing a driven ring and a plate ring respectively with one of them in a rotary shaft and the other in a housing through both the O rings further both the rings coming into slide contact with each other and gluing a polytetra fluoroethylene (PTFE) sheet to a surface, brought into contact with the internal space of a compressor, of the O ring.

CONSTITUTION: A driven ring 3, which rotates with a rotary shaft 1, is brought into slide contact with a plate ring 2 through which the rotary shaft 1 penetrates, and fluid is prevented from its leakage from a sliding surface. Further the leakage is prevented by sealing between the plate ring 2 and a housing 4 and between the driven ring 3 and the rotary shaft 1 respectively by rubber made O rings 5, 6. While a polytetrafluoroethylene (PTFE) sheet 13 is glued to a surface, brought into contact with contact with the internal space of a compressor, of the O ring. This PTFE sheet prevents a rubber member 12 from coming into contact with the sealed fluid and from corroding, while the O rings 5, 6, being prevented from worsening their flexibility because the hard PTFE sheet 13 is glued only to one side, can be easily mounted to a grooved part.