ln this paper, the optimum design of electrical apparatus using design variable parametrization is presented. For analysis and design, the finite element method and the design sensitivity method is used, respectively. By applying the parametrization of the design variables, the obtained designed shape is continuous and smooth. For the parametrization the Bezier spline is used. The designed shape with parametrization is characterized by the control points. By delivering control points to the commercial CAD packages or NC machines, the exact designed shape can be realized in the manufacturing the electrical apparatus. The designed results with and without parametrization are compared and the validity of the parametrization is verified.