PROBLEM TO BE SOLVED: To improve reliability of a superconducting magnet against quench prevention by reducing eddy current heat generation due to magnetic field change caused by vehicle oscillation during traveling.
SOLUTION: The thickness of a low electrical resistance material layer 20 is partly changed, where the layer covers a surface or is plated on the surface of a superconducting coil accommodating vessel 2 which cools a superconducting coil 1 and fixes it to a specified position. In particular, the thickness of low electric resistance material layers 21, 22 of levitating direction upper side region where an eddy current is liable to be generated by magnetic field change of low frequency is increased, and the electric resistance value is reduced. A radiant heat shield and a vacuum thermal insulation vessel which surround the accommodating vessel 2 may be constituted of low electric resistance material in which the plate thickness in a region where an eddy current is liable to be generated in increased. The thickness of the low electric resistance material layer may not be increased but material having low resistivity may be used.