PURPOSE: To enhance the productivity of the title system by a method wherein a wasteful time for waiting a lot is eliminated and a lot is always started in a main treatment device.

CONSTITUTION: A lot is shipped from a warehouse 13 by a conveyance device 17 and conveyed to a preparatory treatment device 12 by a conveyance controller 20 for a semiconductor manufacturing control system 1 when, at every lot, the operating efficiency of a preparatory treatment device ready to a treatment is larger than the operating efficiency of a preparatory treatment device in a present process from a limit earliest shipping schedule time not causing the deterioration of the quality of a lot after a preparatory treatment up to a limit latest shipping schedule time not causing a vacant time due to the waiting of a lot in a main treatment device 11. When the operating efficiency of the preparatory treatment device 12 ready for the treatment is lower than the operating efficiency of the preparatory treatment device 12 in the present process, the operating efficiency of the preparatory treatment device 12 is computed repeatedly until the operating efficiency of the preparatory treatment device 12 ready for the treatment becomes larger than the operating efficiency Of the preparatory treatment device 12 in the present process.