Industrialization of ferrite core had been attained 25 years ago in this country. The ferrite industry already developed to higher level, both in economical and technical fields, has been a vital element to modern electronics industry. This rapidly growing industry requires ferromagnetic oxide substance of high performance characteristics but it has been very difficult to satisfy such requirement on the initial phase. The material available at that time was those having on magnetic. changes in characteristics ; it is called non-magnetic after-effect substance. This research consists of a part of the experiment report describing the results of a study to resolve the above-mentioned problem. In our research the subject is resolved from a chemical standpoint, therefore, a relation to theory of vacancy in the physical term shall be adjusted in the future in connection with the aforesaid standpoint.