When temperature raising is performed, temperature of a superconducting cable is uniformly raised over an entirety of the superconducting cable. The superconducting cable assumes a linear shape when cooled, and deforms into a helical shape when temperature raising is performed. In a former having a twisted wire structure, twisting directions of an outermost layer and a layer next to the outer most layer are set to be the same, enabling stabilization of the helical deformation of the superconducting cable including the former when the temperature raising is performed.