PURPOSE: To obtain an electric conductor having no shrinkage cavity due to shrinkage of solidification upon molding the conductor of a rotor by filling the core of the rotor with molten conductor material by pressure.

CONSTITUTION: In a rotor core 1 laminated on a temporary shaft 3, the core 1 is filled with molten conductor material by pressure to form conductor materials in end rings, fins, and slots of upper and lower parts of the same, then, the molten conductor material is pressurized locally by a pressurizing punch 9 provided at the intermediate part of the upper fin especially by the amount of volume in accordance with the amount of shrinkage of solidification of the molten conductor material while the pressurizing punch 9 is constituted so as to retain the pressure until the final solidification is finished. According to this method, the local pressurizing is effected until the final solidification of the molten conductor material is made whereby a sound rotor conductor having no shrinkage cavity can be obtained.