A gas turbine rotor warming structure comprises a tubular member having an axially extending central through hole and a plurality of fine holes formed in a side wall thereof. The tubular member is inserted in central holes of rotor disks each having blades so as to form an annular gap between the inner surfaces of the central holes and the outer surface of the tubular member. The plurality of fine holes of the tubular member are formed so as to face the inner peripheral surface of the central holse of the rotor disks, so that gas extracted from a compressor is injected into the annular gap through the fine holes and impinges on the inner peripheral surfaces of the rotor disks, whereby inner peripheral portions of the rotor disks are warmed at the time of starting of the gas turbine. The extracted compressor gas which has warmed the inner peripheral portions of the rotor disks passes between the disks and cools the turbine blades.