Iron-based soft magnetic materials are widely used as cores, such as transformers, motors, and generators. The soft magnetic materials developed by the JFE Steel Group include grain oriented electrical steels, non-oriented electrical steels, Super Core (6.5%Si-Fe), soft ferrites, and iron powder. The applications of these soft magnetic materials cover a wide range of frequencies, from commercial frequency to approximately 1 MHz. In addition to improving the properties of individual materials, the JFE Steel Group also investigates the optimum methods of applying these diverse materials through the evaluation of transformers and motors.