Studies on the robotization of agricultural vehicles have been conducted to perform labor-saving, highprecision operations, etc. Component technologies for the robotization were described in general, along with navigation systems. As an example of robotized vehicles, we planned to develop a tilling robot, To recognize the position with an error less than 5 cm and at intervals less than 1 s, we developed 3 types of navigation systems; an off-the -wire type, a kinematic global positioning system (GPS) with inertial navigation system (INS) type and an optical type.