A superconducting magnet includes: a superconducting coil for generating a
static magnetic field; a refrigerant container for containing the
superconducting coil and a refrigerant; a vacuum container for holding
the refrigerant container in a vacuum state; a radiation shield between
the refrigerant container and the vacuum container; a refrigerator for
re-liquidfying the refrigerant; and a dynamic magnetic field shield. The
refrigerator includes: first and second regenerative refrigerants. The
dynamic magnetic field shield is an electric good conductor and arranged
around the first regenerative refrigerant along a motion axis of the
first regenerative refrigerant, wherein a direction of the motion axis is
aligned with a direction of a magnetic force line of the static magnetic
field at the first regenerative refrigerant.