An apparatus for controlling operation of an autonomously navigating utility vehicle equipped with a prime mover to travel about a working area delineated by a boundary line, there are provided with a map generating unit that that generates a working area map comprised of an array of a plurality of cells, a memory unit that counts and memorizes a number of times the vehicle passes over each of the cells based on the detected vehicle position a target cell setting unit that selects one of the cells based on the memorized counted number and sets the selected one as a target cell and a travel controlling unit that controls operation of the prime mover to make the vehicle travel about the working area until the vehicle has reached the boundary line, and make the vehicle turn toward the target cell and then travel straight forward when the vehicle has reached the boundary line.
