Repair method of rotor

A repair method of a rotor including a rotor body extending in an axial direction about an axis and a plurality of impellers arranged in the axial direction and fixed to the rotor body, the repair method comprising:

• a step of performing welding on a repair area of the rotor body to fill a damaged portion formed to be recessed from an outer surface of the rotor body with a welded portion;
• a step of performing annealing treatment only on the repair area in the rotor after the welding is performed;
• and
• a step of scraping a part of the welded portion after the annealing treatment is performed, to form a processing surface smoothly connected to the outer surface, wherein
• the repair area is formed in an axial end area including an end of the rotor body in the axial direction,
• the processing surface is formed at a certain distance from the axis over an entire circumference of the rotor body, and
• the annealing treatment comprises:
• winding a heater around only the repair area;
• winding a heat insulating material to cover the repair area together with the heater;
• and
• performing annealing only on the repair area over an entire circumference in a state in which the heater and the heat insulating material are attached to the repair area including the welded portion.