In an apparatus for controlling operation of an autonomously navigating utility vehicle travelling about a working area delineated by a boundary wire, there are provided with a pair of magnetic sensors, a turning angle detector, a travel distance detector, a travel controlling unit controlling the vehicle to travel along the boundary wire based on the magnetic field strength detected by one of the magnetic sensors while positioning other of the magnetic sensors inside the boundary wire, a route generating unit generating a travel route along a boundary of the working area based on the turning angle and the travel distance, a memory unit memorizing the magnetic field strengths detected by the other of the magnetic sensor in association with the travel route, and a position identifying unit identifying a position of the vehicle by comparing the detected magnetic field strengths with the memorized magnetic field strengths.