A high performance sealing device having an excellent pressure resistance and realizing a prevention of damage. The sealing device usable at a working pressure of 0 to 2 MPa, and not damaged even if the pressure of high-pressure fuel of 5 MPa or higher is applied thereto, wherein high pressure fuel on the high pressure side H is sealed by a first seal part 2, oil from a cam side on a low pressure side L is sealed by a second seal part 3, and the fuel slightly leaked due to failure of scraping at the first seal part is sealed by the second seal part to form a dual seal structure, and a resin ring 21 coming into slidable sealing contact with a shaft 10 is used in the first seal part 2, whereby abnormal abrasion does not occur even when fuel having less lubricity is used, and the durability of the seal is increased.