The invention utilizes a characteristic of superconducting coils that they have high thermal conductivity in a direction of winding. A part of the superconducting coils is thermally connected with liquid helium through thermal anchors so that the part of the superconducting coils can be cooled to the liquid helium temperature. This cooling structure maintains thermal stability of a superconducting MRI magnet even in a condition that a refrigerator stops for a certain period of time, and reduces a manufacturing cost of the superconducting magnet.