In this paper, novel guidance method in which the path planning and following are integrated is proposed.The path planner provides the optimal trajectory minimizing the integral square curvature and the optimal feedback input.The input is used for path following with the PD controller for the cross-track error.The simple kinematic model which is so called unicycle is assumed.Simulations where the steady wind disturbance and initial position errors are considered is conducted to demonstrate adaptive capability of the proposed method.