There are provided a seal fin, a seal structure, and a turbo machine that can achieve a high leak-suppressing effect and can reduce leak loss of the turbo machine. The disclosure suppresses leak of a fluid from a gap between a first structure being in a static state and a second structure rotating around an axis line and is formed on the first structure so as to extend toward the second structure while keeping a clearance between a tip face thereof on an extending direction and the second structure. The first structure and the second structure face each other in a radius direction with the gap inbetween. A plurality of hollows opening at a tip on the extending direction are arranged along a circumference direction in parallel with each other on a front face facing an upstream side of a flow direction of the fluid.