A magnetic refrigerator comprising a magnet generating a high-intensity magnetic field, a tubeshaped superconducting magnetic shield, a magnetic working material and a reciprocating means for reciprocatively moving the superconducting magnetic shield or the magnetic working material, the magnetic refrigerator being arranged such that a magnetization process wherein the magnetic working material is magnetized in the high-intensity magnetic field and a demagnetization process wherein the magnetic working material is demagnetized by being accommodated in the hollow section of the magnetic shield are repeated by the reciprocating means so that the magnetic working material generates coldness. By using the property of a tube-shaped superconductor which can shield the magnetism of an external magnetic field passing through the hollow section of the tube and can generate a zerointensity magnetic field in the hollow section, the magnetic working material magnetized in the highintensity magnetic field generated by the magnet is inserted into the hollow section of the tube-shaped superconducting shield and is demagnetized in an adiabatic condition to generate coldness. This coldness is used to cool the target cold bath.
