The efficiency of traction motor is directly related to the fuel economy of eco-friendly vehicle. To improve the efficiency of the motor, various technologies have been developed which reduce the main loss factor ? the copper loss arising from winding section and the core loss arising from laminated core. The purpose of this study is to improve the efficiency of the motor by reducing the core loss. By applying the new method of lamination that does not damage the electrical steel sheet and insulation between the sheets, the magnetic loss of core is minimized. In addition, the cohesion and rigidity of laminated core has improved compared to traditional methods, so the productivity and NVH characteristics of motor is improved also.