A superconducting electron beam generator comprising a cavity resonator situated in a refrigerator and containing a superconductive metal member fixed on the cavity end plate, a tip of which member is disposed at the strongest point of a high frequency electric field formed in the cavity. A high quality and high energy coherent electron beam is emitted by the electric field from the tip of the metal member along an axis of the cavity and derived through a minute hole formed through the opposite end plate. This superconducting electron beam generator is particularly suitable for a high resolution electron microscope, a high quality X-ray generator, a crystallographic electron beam apparatus and the like.