In 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 wire laid thereat in order to perform work autonomously, there are provided with a working region establishing unit that divides the working area into multiple regions by an imaginary boundary line designated by an operator and establishes a preferential working region in the working area, and a travel controlling unit that controls operation of the prime mover to make the vehicle travel autonomously in the preferential working region, discriminates whether the vehicle has reached the imaginary boundary line based on a detected vehicle position detector, and when the vehicle has reached the imaginary boundary line, controlling operation of the prime mover to make the vehicle turn toward inside of the preferential working region.