There is provided a superconducting magnet in which magnetization caused by a shielding current of a superconducting winding is eliminated whereby the current to be supplied to the superconducting winding is uniformized, and thus uniformity of the central magnetic field is secured. The superconducting magnet has a superconducting winding composed of a superconductor, and an outer AC winding composed of a superconductor or non-superconductor wound coaxially with the superconducting winding, at an outer side the superconducting winding; and an AC current is supplied to the outer AC winding thereby applying an AC magnetic field in a direction perpendicular to a direction of magnetization caused in the superconducting winding by the shielding current, and thus the magnetization is eliminated. Also, the superconducting magnet has an inner AC winding composed of a superconductor or non-superconductor wound coaxially with the superconducting winding, at an inner side of the superconducting winding layer.