This paper presents an improvement of the traction method that was proposed as a solution of shape optimization problems of domain boundaries in which boundary value problems of partial differential equations are defined. Using the theory of the gradient method in Hilbert space the principle of the traction method is presented. Based on the principle a new method is proposed by selecting another bounded coercive bilinear form from the previous method. The proposed method obtains domain variation with solution of a boundary value problem with the Robin condition using the shape gradient. With respect to a three-dimensional bar problem with notch that was not solved with the previous method the proposed method obtained smooth convergence.
