PROBLEM TO BE SOLVED: To provide technology capable for efficiently generating guidance lines even in a polygonal farm field, and to provide a farm field guidance system which is constituted in such a way that data of headlands can be inputted therein, and which can generate turning-routes at the headlands.SOLUTION: On the basis of polygonal data of a farm field, a farm field guidance system can generate an arbitrary operating line for every operating condition. Furthermore, on a guidance screen, the farm field guidance system can display not only a farm field layout and guidance lines, but also a background map including roads, ridges, canals, buildings, facilities, obstructions, and so on, so that the farm field guidance system can perform operations even at night.
