Provided is an unmanned transfer system, which can determine a transfer route automatically, which need not monitor the detailed position and the lapse time of a transfer instrument, which needs none of a sensor, a communication route and a calculating device, which needs no high precise prediction, which can select a proper route even if the system fails in a congestion prediction, and which can spare the energy. Also provided is a transfer route determining method for the unmanned transfer system. A storage device (17) stores a graph (1), in which transfer points, branching points, merging points, transfer origins and transfer destinations of a transfer instrument (11) are set to ''points'' (2), in which the routes directly traced from the individual points to adjoining points are set to ''branches'' (3), and in which the sums of ''time loads'' proportional to the lapse time periods of the individual branches and ''energy loads'' proportional to the consumed energies are set to ''weights'' (4). A transfer control device (18) decides the route, for which the sum of the weights of the individual branches constituting the transfer routes from the transfer origins to the transfer destinations is the minimum, as ''scheduled routes'', adds a predetermined weight to the current ''weights'' (4) of the individual branches of the scheduled routes determined, transfers the individual articles by controlling the transfer instruments individually along the determined scheduled routes, and subtracts the aforementioned predetermined weights from the current weights of the individual branches of the scheduled routes used for the transfers.