A virtual production line indicating an object (e.g., a vehicle) sequence for an actual production line and objects (e.g., vehicles) planned in the future is updated based on a long-term production plan, a fixed production plan, and actual production results. Then, the ordering timings for the parts necessary for the respective objects in the virtual production line are calculated based on the timing for using the parts and the delivery lead time, and the orders are placed according to those timings.