In response to a transfer request, for which a loading time at a transfer source and a loading time at a transfer target are designated by a production controller, there is created a transfer scenario, which contains a basic transfer (From) from the transfer source to a buffer near the transfer target, for example, and a basic transfer (To) from the buffer to the transfer target. In order that the basic transfers (From, To) may be able to be executed, the buffer is reserved, and a transfer vehicle is allocated. The time period for the transfer vehicle to run to the transfer source or the buffer and the time period for the transfer vehicle to run from the transfer source or the buffer are estimated to assign a transfer command to the transfer vehicle. The possibility that the loading and the loading time may deviate from a designated period is evaluated. In case this possibility is high, a production controller is informed that a just-in-time transfer is difficult.