A sealing device seals an annular gap between a shaft and a housing, and includes a first annular member 200 provided with a first cylindrical part 201 that is secured to an outer circumferential surface of the shaft 20, and a first flange 202 extending radially outward from the first cylindrical part 201; a second annular member 300 provided with a second cylindrical part 301 that is secured to an outer circumferential surface of the first cylindrical part 201, and a second flange 302 extending radially outward from the second cylindrical part 301; and an endless resin sealing ring 400 disposed between the first flange 202 and the second flange 302, the sealing ring providing a seal between itself and a shaft hole in the housing 30, and between itself and one of the first flange 202 and the second flange 302 on a low pressure side.