The sealing device includes: an outer peripheral ring 2000 that is in contact with a side wall surface of an annular groove 4100 at a low pressure side (L), and slides with respect to an inner peripheral surface of a shaft hole in a housing 5000 through which a shaft 4000 is inserted. An inner peripheral ring 3000 made of a rubber-like elastic body that is in contact with an inner peripheral surface of the outer peripheral ring 2000 and a groove bottom surface of the annular groove 4100, respectively. The outer peripheral ring 2000 is formed on its outer peripheral surface with a concave portion 2220 which extends from an end of a high pressure side (H) to a position which does not arrive at an end of a low pressure side, so as to introduce fluid thereinto from the high pressure side.