Seal device for piston rod

A piston seal device has a combined oil scraping ring that includes a steel annular oil scraping ring body having an M-, I- or H-shaped cross section, and an annular coil spring. The ring body has a cross-sectional cut at one location and includes an upper rail member, a lower rail member and a strut holding the upper and lower rail members and having an annular groove in its outer circumferential side, the annular groove having a number of circumferentially spaced oil holes. The annular coil spring is fitted into the annular groove in a stretched state for urging the strut diametrically inward toward the piston rod, whereby the inner circumferential surfaces of the upper and lower rail members are brought into pressured contact with the outer peripheral surface of the piston rod owing to the constraining force of the spring. The oil scraping ring contacts the outer peripheral surface of the piston rod while flexing to follow up the shape of the surface, thereby improving the oil sealing effect.