Abstract: A valve device which can reliably seal water even after a long continuous use. It has a valve seat made of a hard ceramic having a fluid passage and a valve body made of a self-lubricating polyphenylene sulfide resin and slidably put on the valve seat. Inlet passages are formed in the valve body. The surface of the valve body to be brought into sliding contact with the valve seat is lapped into a flat or crowned smooth surface after swelling the valve body with liquid. Otherwise, the valve seat and the valve body are made of synthetic resins that show no adhesion to each other. The base and the valve seat may be integrally formed. Also, elastic packings may be provided on the end face of the base so as to protrude into the bottom openings of the inlet passages. Small-dimater flanged rings are fixed in position by the elastic packings.