PURPOSE: To curtail operation cycles by independently providing vacuum exhausting apparatus respectively to the irradiation shield and vacuum container on the occasion of forming a superconductive magnet apparatus by surrounding a helium container accommodating a superconductive magnet with a radiation shield internally provided with multilayer temperature insulating material and further by surrounding the entire part with a vacuum casing.

CONSTITUTION: A coil 1 obtained by winding a superconductive material is housed in a helium container 2 filled with liquid helium and it is then surrounded by a radiation shield 3. At this time, the internal wall of shield 3 is provided with multilayer temperature insulating material 3b which has a structure of several tens of layers where polyester net is stacked on a thin layer vacuum- depositing aluminum on miler, while the external circumference is wound by a cooling tube 3a which allows liquid nitrogen or low temperature helium gas to flow, thereby forming an individual container 3c. This container is then surrounded by a vacuum container 4 having the heat insulating function by the vacuum condition, and the vacuum exhaustion apparatuses 7 and 6 are provided respectively to the individual container 3c and vacuum container 4. Thereby, the vacuum exhaustion period can be curtailed.