A fluid sealing mechanism for sealing fluid being fed into a fluid pressure pocket formed between sliding surfaces which are formed on the opposing surfaces of an article being supported and a support for supporting the article, wherein a ring groove being fitted with a resilient ring for sealing fluid is made in the sliding surface of the support. Under a state where a regulation ring for preventing the resilient ring from jumping out of the ring groove is fitted over the re-silient ring, the regulation ring is fitted in the ring groove along with the resilient ring. When the fluid fed into the fluid pressure pocket reaches a specified pressure, the regulation ring comes into pressure contact with the sliding surface of the support along with the resilient ring, thus preventing the resilient ring from jumping out.