A rotating machine includes a casing (10) having a cavity (12) that a tip of a rotor blade enters, a plurality of sealing fins (17) extending from an inner circumferential surface of the cavity (12) of the casing (10) toward the tip of the rotor blade (50) and configured to seal a space between the casing (10) and the rotor blade (50), and swirl breakers (2) disposed between the plurality of sealing fins, extending from the inner circumferential surface of the cavity (12) of the casing (10) inward in the radial direction, and having swirl flow collision surface (3) with which a swirl flow collides and swirl flow transmission parts (n) formed at at least parts of the swirl flow collision surfaces (3) and through which the swirl flow passes in a circumferential direction.