A gradient Si steel sheet shows low iron loss in the high frequency range and lower iron loss deterioration under compressive stresses, therefore, it is suitable for use as the core material of high-speed motors, which have seen considerable downsizing in recent years. By performing shearing and shrink-fitting, the advantages of gradient Si steel as a motor material are investigated in this study. In both shearing and compressive stress experiments, gradient Si steel showed lower iron loss compared to conventional non-oriented electrical steel (0.2mm thick). By numerical simulation, the efficiencies of the shrink-fitted motors using gradient Si steel and 3%Si steel were calculated. The motor using the gradient Si steel showed significantly higher efficiency than that using the 3%Si steel. Moreover, even under city driving conditions, gradient Si steel showed good efficiency, because of lower iron loss deterioration. Therefore, gradient Si steel can be used for a wide variety of motors in addition to high- frequency devices.