A turbine comprising: a blade disposed on a shaft body rotating around a rotary axis; wherein a tip shroud extending in a circumferential direction is installed at a tip section of the blade; a structure, configured to surround the blade and installed at a tip section side of the blade via a gap; at least two step sections formed at one of the tip shroud of the blade and a section of the structure opposite to the tip shroud and protruding toward the other of the tip shroud and a section of the structure opposite to the tip shroud; each step section having a step surface (53A, 53B, 53C) and an upper surface (152A, 152B, 152C); and; at least two seal fins corresponding to the at least two step sections, respectively, the at least two seal fins being formed at the other of the tip shroud of the blade and the section of the structure opposite to the tip shroud, extending toward the corresponding step sections, respectively, and configured to form a respective micro gap between the corresponding step sections and the seal fins; wherein protruding heights of the step sections are gradually increased from an upstream side toward a downstream side; characterized in that inclined sections are formed at each of the step surfaces (53A, 53B, 53C), the inclined sections being inclined from the upstream side toward the downstream side; and the inclined sections comprise an upper edge section of each step surface, said upper edge section being respectively connected to the adjacent upper surface (152A, 152B, 152C); an inclination angle of each inclined section with respect to a radial direction of the rotary axis is set to be larger for the inclined section formed at the step surface located in the downstream side. a blade disposed on a shaft body rotating around a rotary axis; wherein a tip shroud extending in a circumferential direction is installed at a tip section of the blade; a structure, configured to surround the blade and installed at a tip section side of the blade via a gap; at least two step sections formed at one of the tip shroud of the blade and a section of the structure opposite to the tip shroud and protruding toward the other of the tip shroud and a section of the structure opposite to the tip shroud; each step section having a step surface (53A, 53B, 53C) and an upper surface (152A, 152B, 152C); and; at least two seal fins corresponding to the at least two step sections, respectively, the at least two seal fins being formed at the other of the tip shroud of the blade and the section of the structure opposite to the tip shroud, extending toward the corresponding step sections, respectively, and configured to form a respective micro gap between the corresponding step sections and the seal fins; wherein protruding heights of the step sections are gradually increased from an upstream side toward a downstream side; characterized in that inclined sections are formed at each of the step surfaces (53A, 53B, 53C), the inclined sections being inclined from the upstream side toward the downstream side; and the inclined sections comprise an upper edge section of each step surface, said upper edge section being respectively connected to the adjacent upper surface (152A, 152B, 152C); an inclination angle of each inclined section with respect to a radial direction of the rotary axis is set to be larger for the inclined section formed at the step surface located in the downstream side.