In an apparatus for controlling operation of an autonomously navigating utility vehicle adapted to run about a working area defined by a boundary wire which generates magnetic field therearound when supplied with electric current and having a magnetic sensor that produces an output indicating intensity of magnetic field generated by the boundary wire and a position determining unit that determine a position of the vehicle with respect to the working area based on the output of the magnetic sensor, a coded data signal determined to be inherent to the working area is generated and supplied to the electric current, and the position determining unit detects the data signal and determines the position of the vehicle based on a rate of concordance of the detected data signal and a reference signal (42, S12 - S28).
