Labyrinth seal and gas turbine

A labyrinth seal comprising:

• a first structure;
• and
• a second structure opposed to the first structure, wherein:
• the first structure includes
• seal fins located at intervals in an axial direction and extending toward the second structure,
• a downstream wall surface located downstream of a most downstream one of the seal fins and extending toward the second structure, a tip of the downstream wall surface being located at a side of a tip of the most downstream seal fin, the side being close to the second structure in a radial direction, and
• a first outlet surface extending from the tip of the downstream wall surface toward a downstream side in the axial direction;
• and
• the second structure includes
• a second outlet surface opposed to the first outlet surface, a radial gap being between the first outlet surface and the second outlet surface, and
• a cavity surface located upstream of the second outlet surface in the axial direction and adjacent to the second outlet surface, the cavity surface being recessed in a direction away from the first structure.