A turbine rotor for use in a gas turbine, comprising: a column-shaped rotor body portion; a plurality of turbine disks projecting to a radially outer side from an outer peripheral surface of the rotor body portion over a circumferential direction and provided in a center axis direction of the rotor body portion to form a plurality of turbine stages; a first cooling passage portion formed in the rotor body portion and a second cooling passage portion formed in the rotor body portion, characterized by the first cooling passage portion to which a first cooling medium is supplied, and the first cooling passage portion that discharges the first cooling medium to the high-pressure side turbine stage, which is the high-pressure side out of the turbine stages; the second cooling passage portion to which a second cooling medium whose pressure is lower than the pressure of the first cooling medium is supplied, and the second cooling passage portion that discharges the second cooling medium to the low-pressure side turbine stage, which is the side lower in pressure than the high-pressure side turbine stage, wherein the first cooling passage portion includes: a first axial passage formed in the center axis direction of the turbine rotor; a first introduction passage that introduces the first cooling medium into the first axial passage; and a first discharge passage that discharges the first cooling medium to the high-pressure side turbine stage from the first axial passage, and the second cooling passage portion includes: a second axial passage formed in the center axis direction of the turbine rotor; a second introduction passage that introduces the second cooling medium into the second axial passage; and a second discharge passage that discharges the second cooling medium to the low-pressure side turbine stage from the second axial passage. a column-shaped rotor body portion; a plurality of turbine disks projecting to a radially outer side from an outer peripheral surface of the rotor body portion over a circumferential direction and provided in a center axis direction of the rotor body portion to form a plurality of turbine stages; a first cooling passage portion formed in the rotor body portion and a second cooling passage portion formed in the rotor body portion, characterized by the first cooling passage portion to which a first cooling medium is supplied, and the first cooling passage portion that discharges the first cooling medium to the high-pressure side turbine stage, which is the high-pressure side out of the turbine stages; the second cooling passage portion to which a second cooling medium whose pressure is lower than the pressure of the first cooling medium is supplied, and the second cooling passage portion that discharges the second cooling medium to the low-pressure side turbine stage, which is the side lower in pressure than the high-pressure side turbine stage, wherein the first cooling passage portion includes: a first axial passage formed in the center axis direction of the turbine rotor; a first introduction passage that introduces the first cooling medium into the first axial passage; and a first discharge passage that discharges the first cooling medium to the high-pressure side turbine stage from the first axial passage, and the second cooling passage portion includes: a second axial passage formed in the center axis direction of the turbine rotor; a second introduction passage that introduces the second cooling medium into the second axial passage; and a second discharge passage that discharges the second cooling medium to the low-pressure side turbine stage from the second axial passage. a first axial passage formed in the center axis direction of the turbine rotor; a first introduction passage that introduces the first cooling medium into the first axial passage; and a first discharge passage that discharges the first cooling medium to the high-pressure side turbine stage from the first axial passage, and the second cooling passage portion includes: a second axial passage formed in the center axis direction of the turbine rotor; a second introduction passage that introduces the second cooling medium into the second axial passage; and a second discharge passage that discharges the second cooling medium to the low-pressure side turbine stage from the second axial passage. a second axial passage formed in the center axis direction of the turbine rotor; a second introduction passage that introduces the second cooling medium into the second axial passage; and a second discharge passage that discharges the second cooling medium to the low-pressure side turbine stage from the second axial passage.