These days, tracking control with high speed and high accuracy is seriously required in the field of robotics and machine tool. Until now, the control system has been synthesized by defining performance index including position error term on the trajectory in order to realize the purpose. However, satisfactory performance of the machine is not obtained because the position error does not represent the trajectory error which is to be really evaluated in the control problem, although it is deeply related to the trajectory error. In this paper, we propose new method in which the trajectory error area produced by the diference between the desired trajectory and the tracked one by the machine is evaluated in the performance index, and optimal preview control system is synthesized by means of optimal regulator theory. This system utilizes the future desired signal up to finite future time from present time. That means this system is preview control system. First, the control method evaluating the position error on the trajectory is discussed by exemplifying two-car tracking problem and the demerits to be overcome are pointed out. Then, concept of evaluating tracking error area is explained and proposed, and its formulation is discussed and it is shown that the trajectory error term is described by quadratic form with time varying coefficients. Next, the synthesis method of the preview control system with the trajectory error area term is presented. To evaluate the effectiveness of the proposed control system, simulation studies for two axis position controller are carried out.