The automatic following control sq stem is presented. In order to save time and labor in farming, this control system allows one operator to utilize more than one machine simultaneously In this system a computer-controlled vehicle chases the operator-controlled vehicle. Ultrasonic sensors are used to measure the relative position between vehicles. The sensors,cere installed on two head-feeding combines. Furthermore, each combine mounted an RTK-GPS in order to measure the travelling locus of the combine precisely Chase experiments by two combines were performed on the road and the field Consequently, the presented system successfully demonstrated high accuracy regardless offset.