For delivering parts successively received in shipment units by parts deliverer to part use positions, the delivering operation time required for each parts deliverer is uniformalized. A uniformalizing plan is produced, and the delivering operation is continued according to the plan. The delivering operation time is calculated for each shipment unit (first step). The assignment of shipment units to parts deliverers is shifted such as to uniformalize the delivering operation time for each parts deliverer (third step). The shifting operation is continued until uniformalizing is obtained. As a result, uniformalized assignment can be realized.