Abstract: A method of an unmanned vehicle comprises the steps of placing a certain number of ground marks each of which comprises a plurality of line segments on a passage of the vehicle measuring amount of movement of the vehicle between the adjacent line segments when the vehicle moves across each of the ground marks, and obtaining a relative positional relation between the ground mark and the vehicle with reference to the amount of movement thereof whereby movement of the vehicle is properly guided in accordance with the thus obtained positional relation. In the case of a navigational guiding method typically employed in aircraft or ship, an estimated position of the vehicle is corrected with reference to the aforesaid relative positional relation.