Turbine blade and gas turbine

A turbine blade comprising:

• an airfoil portion that extends in a blade height direction and that includes a pressure surface and a suction surface extending between a leading edge and a trailing edge;
• and
• a shroud portion that is positioned closer to a blade tip side than the airfoil portion is,
• wherein a trailing edge side end portion of the shroud portion includes
• a trailing edge side contact surface that has a normal line extending along a chord direction of the airfoil portion and that is formed to face a trailing edge side in the chord direction, and
• a trailing edge side curved surface that is connected to an end portion of the trailing edge side contact surface on a leading edge side as seen in the blade height direction,
• a leading edge side end portion of the shroud portion includes
• a leading edge side contact surface that has a normal line extending along the chord direction and that is formed to face a leading edge side in the chord direction, and
• a leading edge side curved surface that is connected to an end portion of the leading edge side contact surface on a trailing edge side as seen in the blade height direction, and
• at least one of a first condition and a second condition is satisfied on an assumption that a radius of curvature of the trailing edge side curved surface at a first position as seen in the blade height direction is a first radius of curvature, the radius of curvature at a second position, which is farther from the trailing edge side contact surface than the first position is, as seen in the blade height direction is a second radius of curvature, a radius of curvature of the leading edge side curved surface at a third position as seen in the blade height direction is a third radius of curvature, the radius of curvature at a fourth position, which is farther from the leading edge side contact surface than the third position is, as seen in the blade height direction is a fourth radius of curvature, the first condition is regarded as satisfied in a case where the trailing edge side curved surface has a region that is recessed to be closer to the leading edge side than an extension line of the trailing edge side contact surface is as seen in the blade height direction and the second radius of curvature is smaller than the first radius of curvature, and the second condition is regarded as satisfied in a case where the leading edge side curved surface has a region that is recessed to be closer to the trailing edge side than an extension line of the leading edge side contact surface is as seen in the blade height direction and the fourth radius of curvature is smaller than the third radius of curvature.