The tilling robot mainly comprises: a robot vehicle called ROBOTRA, which is remodeled to control parts of commercially available tractors automatically, a navigation system called XNAV, which detects and outputs robot positioning information using an auto-tracking type surveying device, and a controller with read operation software to execute path planning and control the robot vehicle. The robot has ability almost equivalent to that of customary manned-driven tractors and can perform unmanned rotary tilling on a rectangular field. To improve its adaptability during unmanned operation, we remodeled it so that it could perform path operations differing from customary rotary tilling and performed field tests. We proposed two different path operation methods: “diagonal operation”; performing returning straight operations diagonally against the longer side of the field; and “round operation”; performing straight operations parallel to the four sides in the entire field area, and developed a software package for the same. Following field tests using the software, we confirmed that favorable unmanned operation could be achieved through both methods.