Abstract: There are disclosed an oxide superconductor which is made of an oxide superconductive bulk body (e.g. a rare earth element base copper-oxide superconductive bulk body) which has a resin impregnated layer (e.g. epoxy base resin impregnated layer), and, optionally, a proper amount of silver or a silver oxide; and a process for producing the above oxide superconductor which comprises impregnating a resin into an oxide superconductive bulk body by bringing the resin in liquid form into contact with the bulk body which is preserved in an atmosphere of reduced pressure. The above superconductor is capable of assuring a high trapped magnetic field and maintaining its performance for a long period of time without being affected by internal or external forces such as electromagnetic forces or thermal strains or by corrosive environments.