PURPOSE: To control the order load when a production schedule plan is produced.

CONSTITUTION: All orders of a production plan storage part 1 are piled on the load at a load piling part 2 and stored in a load piling storage part 5. The process ability information of a process ability data storage part 4 and the order load piling information are shown at an ability-load collation display part 5 together with the load control information. Both the starting date of each process and the production ending date set with the change of the production starting date of the order to be controlled are changed at a process starting date control part 11. Meanwhile the production starting date, the process starting date, and the production ending date are changed at a process lead time control part 8 based on the change of the order lead time. Thus the load is controlled.