A rotor that is intended to be rotatably supported, the rotor including a turbine disk (31a,31b) and a plurality of rotor blades (22a,22b) that are arranged in a respective plurality of fitting grooves on a circumference of the turbine disk (31a, 31b) in a circumferential direction, the turbine disk (31a,31b) comprising: a plurality of first cooling holes that penetrate the turbine disk (31a,31b) from inside toward outside thereof, that are communicatively connected to a cooling passage provided inside of each of the rotor blades (22a,22b), and that are arranged in the circumferential direction; and second cooling holes that are positioned between each of the first cooling holes and penetrate the turbine disk (31a,31b) from the inside toward the outside thereof, wherein cooling gas is allowed to be supplied from base ends of the first cooling holes and the second cooling holes; characterized in that leading ends of the first cooling holes and the second cooling holes are communicatively connected to a radial direction communicating channel arranged in the circumferential direction, and the fitting grooves arranged on the outer circumference in the circumferential direction are fitted with respective fitting protrusions on the rotor blades (22a,22b) to form axial direction communicating channels in spaces between the fitting grooves and the rotor blades (22a,22b) along an axial direction, wherein the first cooling holes are arranged corresponding to the axial direction communicating channels in the circumferential direction, and the leading ends thereof are communicatively connected to the radial direction communicating channel and the axial direction communicating channels, and wherein the second cooling holes are arranged between the first cooling holes in the circumferential direction, and have the leading ends sealed, and are communicatively connected to the radial direction communicating channel. a plurality of first cooling holes that penetrate the turbine disk (31a,31b) from inside toward outside thereof, that are communicatively connected to a cooling passage provided inside of each of the rotor blades (22a,22b), and that are arranged in the circumferential direction; and second cooling holes that are positioned between each of the first cooling holes and penetrate the turbine disk (31a,31b) from the inside toward the outside thereof, wherein cooling gas is allowed to be supplied from base ends of the first cooling holes and the second cooling holes; characterized in that leading ends of the first cooling holes and the second cooling holes are communicatively connected to a radial direction communicating channel arranged in the circumferential direction, and the fitting grooves arranged on the outer circumference in the circumferential direction are fitted with respective fitting protrusions on the rotor blades (22a,22b) to form axial direction communicating channels in spaces between the fitting grooves and the rotor blades (22a,22b) along an axial direction, wherein the first cooling holes are arranged corresponding to the axial direction communicating channels in the circumferential direction, and the leading ends thereof are communicatively connected to the radial direction communicating channel and the axial direction communicating channels, and wherein the second cooling holes are arranged between the first cooling holes in the circumferential direction, and have the leading ends sealed, and are communicatively connected to the radial direction communicating channel.