A work zone boundary demarcation apparatus to demarcate boundaries that divide a work area (AR) to be serviced by at least one autonomously navigating work machine into multiple zones (ARn), equipped with a computer having at least a processor, a memory, an input-output circuit and a simulation program loaded in the memory to simulate work of the work machine in the work area; wherein the processor is configured to perform as a boundary demarcation unit that demarcates boundaries which divide the work area into multiple zones, a simulation execution unit that executes simulation of work of the work machine in the multiple zones divided by the boundaries demarcated by the boundary demarcation unit, a boundary re-demarcation unit that re-demarcates boundaries demarcated by the boundary demarcation unit based on results of the simulation executed by the simulation execution unit, and a zone display unit that displays the multiple zones divided by the boundaries re-demarcated by the boundary re-demarcation unit.