A sealing device includes a fin, a through hole, and a high pressure fluid supplying unit. The fin extends from a stationary body toward a rotating body in a gap between the stationary and rotating bodies. The fin is not in contact with the rotating body. The through hole is formed to be opened in at least one of the stationary body and the rotating body on an upstream side of the fin in a flow direction of a fluid to flow into the gap between the stationary body and the rotating body. The through hole is opened toward an upstream side of the fluid to flow in the gap between the stationary body and the rotating body. The high pressure fluid supplying unit is configured to supply a high pressure fluid to the gap from the through hole. The high pressure fluid has a higher pressure than the fluid.