Large-scale farming requires comparatively large and heavy agricultural machinery. Because large implements are too heavy to be mounted, trailing implements are commonly used for various agricultural operations. Farm work with these implements requires experienced operators. In particular, steering a trailer backwards requires special driving skill. Even driving forward, when the size of the trailing implement is large, can be a difficult task. For example, it is difficult to drive a tractor and control the edge of the trailing implement so that it follows the demarcation between treated and untreated areas in a field. The difficulty is due to the trailer's slow response and the limitations of operator's sight. For variable rate application done in precision agriculture, an operator has to drive his tractor to track a given path by use of GPS based guidance system. Though a tractor can track the path by following instruction given by the GPS guidance system, path of a trailer could not be well controlled. In the paper a novel hitching control method is described which was developed to improve the tracking ability of a towed trailer. Steering controls of trailer's wheels has been used to get better tracking performance of a trailer. However, the control needs steering mechanism of trailer wheels, consequently cannot apply to conventional trailers. The idea proposed in this paper is that the tracking ability of a trailer can be enhanced by moving a hitching point of a tractor, thereby the control is applicable to any conventional trailer. This paper describes background of the development of the control, theoretical examinations of hitching position control, and checking of the control through computer simulations. Finally advantages and disadvantages of the hitching position control were discussed.