Gas turbine rotor cooling

A gas turbine generally comprises a compressor, a combustor and a turbine body operatively connected to the compressor through a rotation shaft, and the turbine body is composed of a plurality of rotors formed with turbine discs and movable blades which are arranged in plural stages along an axial direction of the turbine body, in which a rear shaft (16) is connected to a downstream side of a final stage disc of the turbine discs (17) so as to extend rearward from the final stage turbine disc (17) and supported by means of a bearing. The rear shaft (16) is formed with a cooling medium supply passage (18) for supplying a cooling medium to the turbine disc (17) and a cooling medium recovery passage (19) for recovering the cooling medium from the turbine disc (17), and a further cooling medium passage (21) is formed between the rear shaft (16) and either one of the cooling medium supply passage (18) and the cooling medium recovery passage (19).