To provide a superconducting magnet device and a magnet resonance imaging device which inhibit heat generation caused by an eddy current due to an external variation magnetic field.

A superconducting magnet device includes: a superconducting coil around which a superconducting wire is wound; a refrigerant container 1 including at least the one superconducting coil with the refrigerant; a shield plate 2 covering the refrigerant container 1; a vacuum container 5 covering the shield plate 2; and an external magnetic field generation source disposed at the exterior of the vacuum container 5. The shield plate 2 has a cutout part 2a and includes: a heat insulation support structure 4 which is fixed to the vacuum container 5 at one end and supports the refrigerant container 1 and the shield plate 2 through the cutout part 2a; and a resistance member 3 which is installed at a peripheral part of the cutout part 2a so as to enclose the cutout part 2a and is electrically connected with the shield plate 2, the resistance member 3 having an electric resistance value equal to or smaller than that of the shield plate 2 and protruding toward the vacuum container 5 side.