A field rotor for a superconducting rotating machine (100) comprises: a rotary shaft (18); a supply shaft (10) for supplying the rotary shaft with a cooling medium at one end of the rotary shaft; an input and output shaft (24) provided to rotate integrally with the rotary shaft at the other end of the rotary shaft; and a superconducting coil (20) held around the rotary shaft to be cooled by the cooling medium. The supply shaft and the input and output shaft are fixed to each other so as to rotate together. The rotary shaft and the supply shaft are in contact with each other at least at one portion so that the rotary shaft is supported by the supply shaft, and are fitted to each other slidably in the circumferential direction and in the axial direction of the rotary shaft.
