Sealing device and sealing structure

A sealing structure comprising:

• a first member that includes a first surface provided with a first space;
• a second member that includes a second surface provided with a second space having a diameter greater than a diameter of the first space, the second member facing the first surface;
• and
• a sealing device provided between the first member and the second member,
• wherein the sealing device includes a tubular elastic body, and
• wherein the elastic body includes:
• a first outer circumferential surface facing an inner circumferential surface defining the first space;
• a second outer circumferential surface facing an inner circumferential surface defining the second space, the second outer circumferential surface having a diameter greater than a diameter of the first outer circumferential surface;
• a step surface defining a difference in level between the first outer circumferential surface and the second outer circumferential surface, the step surface being in contact with the first surface;
• an annular first protrusion protruding from the first outer circumferential surface;
• and
• an annular second protrusion protruding from the second outer circumferential surface.