Abstract: A superconducting deflection electromagnet apparatus for deflecting an electron beam includes a liquid helium reservoir 21 disposed outside of the magnetic shield 11 surrounding the cryostat 4 accommodating the upper and lower liquid helium containers 2 in which coil assemblies 1, 31, 32 are disposed. Preferably, the upper and lower liquid helium containers 2 are supported from the cryostat 4 by means of the thermally insulating support members 5, 6 and 8 whose positions are adjustable by means of the threaded projections 5a, 6a and 8a and the nuts 52, 53, 62, 63, 82, 83 engaging therewith. The nuts secure the respective thermally insulating support members to the cap-shaped fixing members 44, 47, 49 attached to the extensions 43, 45, 49 of the cryostat 4.