A protected region is set for a manned working machine, said region including a first protected region in which new protected region setting request information is not transmitted and which includes the position of the manned working machine, and a second protected region which is set along a periphery of the first protected region and in which new protected region setting request information is transmitted. An area occupied by the vehicle body of the manned working machine on a plane projected on the ground surface is calculated on the basis of vehicle body information indicating the size of the vehicle body of the manned working machine and position information thereof. When the occupied area is present within the first protected region, new protected region setting request information is not transmitted, whereas when the occupied area is present within the second protected region, protected region setting request information is transmitted.