In a superconducting magnet using a high-temperature superconducting wire, even when the cooling by the refrigerator is stopped for a long time due to a power outage or a system failure, it is possible to avoid the deterioration of the heat insulating function of the vacuum tank and, after restarting the freezer, Which can be cooled quickly. To this end, there are provided a superconducting coil 105 for generating a static magnetic field, a vacuum vessel 107 for accommodating the superconducting coil 105, a refrigerator for thermally contacting the superconducting coil 105 and for cooling the superconducting coil 105, and a cooling function for the refrigerator And a vacuum degree lowering prevention unit (205 or the like) for preventing the degree of vacuum of the vacuum container from decreasing in the case where the vacuum degree is reduced or stopped.高温超電導線を用いた超電導磁石において、停電やシステム障害で冷凍機による冷却が長時間停止した場合でも、真空槽の断熱機能低下を回避し、冷凍機の再開後に、高温超電導線の臨界温度以下に速やかに冷却できるMRI装置を提供する。そのために、静磁場を発生する超電導コイル105と、超電導コイル105を収容する真空容器107と、超電導コイル105と熱的に接触し、超電導コイル105を冷却する冷凍機と、冷凍機の冷却機能が低下もしくは停止した場合に、真空容器の真空度が低下を防止する真空度低下防止部(205等)とを有する。
