Sealing device

The objective of the present invention is to provide a sealing device equipped with a resin seal ring and a spring means, wherein the seal ring does not easily deform in the inner circumferential direction when pressure is applied, and thus a gap does not easily occur and the sealing performance can be improved. To achieve this objective this sealing device, which is mounted in a mounting groove provided in one of two members that move relative to one another, and which makes close contact with the other member and the side walls of the mounting groove, thereby providing a seal between the two members, has: a seal ring, the tubular end part of which is provided with a radial part, with the outer circumferential surface of the tubular part making close contact with the other member and the end surface of the radial part making close contact with the side walls of the mounting groove; a support ring, which is manufactured with a hard material such as metal, and which has a region that makes contact with the inner circumferential surface of the tubular part and a region that makes contact with the other end surface of the radial part in the axial direction; and a spring means that presses against the support ring and the seal ring. The support ring has the function of supporting the tubular part of the seal ring from the inner circumferential side thereof.