A magnetic resonance imaging apparatus comprising a vacuum container vacuumized inside thereof, a liquid refrigerant container installed in the vacuum container to store liquid refrigerant therein, a superconducting member installed inside the liquid refrigerant container to be rendered superconductive by being impregnated in the liquid refrigerant and allow current to flow therethrough, and freezing means connected to an insertion port provided in the liquid refrigerant container to re-condense gas evaporated from the liquid refrigerant in the liquid refrigerant container, characterized in that an air flow-in preventing means is provided that raises the pressure in the liquid refrigerant container to prevent air from flowing into the insertion port of the liquid refrigerant container from the outside of the vacuum container.
