is no possibility that this lot is brought to a standby state within the processing system by the lot just before this lot and the operation is completed in the minimum time while when the operation start time difference is small this lot is brought to a standby state by the lot just before this lot and the processing time is increased by the standby time actual results are shown in fig6 wherein the ordinate represents processing time and the abscissa represents start time difference specifically in order to provide an estimate value of the minimum processing time s for lots under respective operation conditions the start time difference t 1 shown in fig6 is used as the threshold value and the processing time in which the start time difference is larger than the threshold value may be estimated as the minimum processing time s for a combination of operation conditions for a certain object lot with operation conditions for a lot just before the object lot when the relationship of the start time difference between both the lots with the end time difference between both the lots is taken into consideration in the case of a small start time difference the.