A rotor (1) of a gas turbine compressor comprises a multiplicity of welded-together rotor disks (3a, 3b, 4, 5), of which two or more rotor disks (3a, 3b), in a radially outer region (9′), are welded together, and, in a radially inner central region (9), are abutment-joined together. Via the abutment-joining of two rotor disks (3a, 3b), a heat flow (8) radially outward from the center of the rotor (1) is achieved so that the material temperature of the rotor (1) can be kept below a predetermined level during operation. As a result, the service life of the rotor (1) can be increased. In one embodiment, one rotor disk (3a), on its surface, additionally has a recess (7) which can be cooled from outside. The rotor disks (3a, 3b) according to the invention, which are welded and abutment-joined together, can especially be used at the last point in the flow direction of the compressor.