To provide a sealing device capable of sealing a high-temperature and high-pressure fluid to be sealed, via a sealing face, and capable of bringing the sealing face into close contact following a displacement between attaching faces.

This sealing device includes the first sealing part 2 having the first elastic part 2C in one side of the first curved part 2B and the second elastic part 2A in the other side, the second sealing part 12 having the first symmetrical elastic part 12C in one side of the second curved part 12B and the second symmetrical elastic part 12A in the other side, a connecting part 3 for connecting the second elastic part 2A of the first sealing part 2 and the second symmetrical part 12A of the second sealing part 12, the first sealing face 2C1 provided on the first side face of the first elastic part 2C, and the second sealing face 12C1 provided on the second side face of the first symmetrical elastic part 12C, and a side face 2A1 of the first elastic part 2C is brought into contact with the side face 12A1 of the second symmetrical elastic part 12A, on a junction face between the connecting part 3 and the curved parts 2B, 12B. The curved parts 2B, 12B are opened, using, as a fulcrum, the junction face changing a position by a force acting between the sealing faces 12C1, 2C1.