A turbine rotor in an embodiment includes: a rotor body portion; and a plurality of turbine disks provided on the rotor body portion in a center axis direction of the rotor body portion. The turbine rotor includes: a high-pressure cooling passage formed in the rotor body portion, the high-pressure cooling passage to which a high-pressure cooling medium is supplied, and the high-pressure cooling passage that discharges the high-pressure cooling medium to the high-pressure side turbine stage; and a low-pressure cooling passage formed in the rotor body portion, the low-pressure cooling passage to which a low-pressure cooling medium whose pressure is lower than the pressure of the high-pressure cooling medium is supplied, and the low-pressure cooling passage that discharges the low-pressure cooling medium to the low-pressure side turbine stage.