PURPOSE: To obtain a conductor with excellent thermal stability, mechanical strength and superconductive characteristics by a construction wherein a number of superconductive wires allowed to have the properties of stabilizing material are contained in a conduit made of metal with excellent mechanical strength and provided with a hollow together with a number of apertures in its periphery for distributing liquid helium.

CONSTITUTION: If conductors are immersed into liquid helium, the liquid helium will enter into a gap between the layers of the conductors and into a conduit 11 through apertures 12 provided in both side surfaces of the conduit 11 for distributing the liquid helium. Consequently, the periphery of a stranded superconductive wire 13 almost thoroughly makes contact with the liquid helium and its thermal stability is by far improved. Since the conduit 11 composed of SUS is not mechanically connected to the stranded superconductive wire 13, the conduit 11 bears almost all of the stress caused by electromagnetic force generated in the longitudinal direction of the conductor, the stress being determined by the allowable stress of the SUS. The stranded superconductive wire 13 is almost free from the stress, whereas the superconductive characteristics will be least deteriorated.