PURPOSE: To provide a superconducting rotor which operates stably without causing quench by absorbing heat intruded from an inner rotor support into an inner rotor effectively and feeding cryogenic refrigerant through the refrigerant flow path in a superconducting field winding only in the inward radial direction at any part thereby maintaining a good heat transmission.

CONSTITUTION: One or a plurality of holes or grooves, i.e., heat siphons 53, having openings only to an inner peripheral side cryogenic refrigerant tank 54 and not communicated with an outer peripheral cryogenic refrigerant tank 51 are provided in the radial direction, with the inner rotor support 17 on the side of winding support tube 9 and the axial end side of the winding support tube 9 being exposed between a superconducting field winding 8, the outer peripheral side cryogenic refrigerant tank 51 and the low temperature end 52 of the inner rotor support 17. Cryogenic refrigerant 5 flows continuously from the inner peripheral cryogenic refrigerant tank 54 into the holes to produce an opposing flow which collects its heat to the cryogenic refrigerant 5.