Turbine rotor and steam turbine

A turbine rotor 300 includes: a high-temperature turbine rotor constituent part 301 where high-temperature steam passes; low-temperature turbine rotor constituent parts 302 sandwiching and weld-connected to the high-temperature turbine rotor constituent part 301 and made of a material different from a material of the high-temperature turbine rotor constituent part 301; and a cooling part cooling the high-temperature turbine rotor constituent part 301 by ejecting cooling steam 240 to a position, of the high-temperature turbine rotor constituent part 301, near a welded portion 120 between the high-temperature turbine rotor constituent part 301 and the low-temperature turbine rotor constituent part 302. A value equal to a distance divided by a diameter is equal to or more than 0.3, where the distance is a distance from the position, of the high-temperature turbine rotor constituent part 301, ejected the cooling steam 240 up to the welded portion 120, and the diameter is a turbine rotor diameter of the high-temperature turbine rotor constituent part 301.