For high quality and high resolution TV's and displays high-performance ferrite cores for deflection yokes are required. Therefore, I undertook fundamental research into the critical items in the ferrite manufacturing process including the starting raw materials, chemical compositions, additives, granulated powder, molding, sintering and microstructure control. Based on this knowledge, I have been able to develop manufacturing technology which has resulted in the industrial production of high-performance deflection yoke cores. In this paper, I describe iron oxide material, sintering technology (process and tools), spray drying method of powder granulation technology (featuring both fluidity improvement and reduction of the holes in the granulation powder) as well as a low loss core development. Moreover, I undertook a computer simulation and, based on the results of heat quantity analysis, I designed materials and succeeded in developing new material (DS1) in which the core loss and heat quantity have been dramatically reduced compared with conventional materials.