A semiconductor manufacturing system having a high processing efficiency and a high product output includes a processing device for simultaneously processing a prescribed number of lots for which it is reserved, and a semiconductor manufacturing system control device connected to the processing device for managing the manufacturing steps. The semiconductor manufacturing system control device includes a lot processing step managing portion for managing the processing steps of the lots and determining whether the lots have arrived at the step of being processed by the processing device; a lot securing portion, connected to the lot processing step managing portion, for selecting, when the lots have arrived at the step of being processed by the processing device, a prescribed number of lots to be processed by the processing device under the same processing condition as the lots, instructing an operator to secure the prescribed number of lots selected, and determining whether the prescribed number of lots are secured; and a lot reservation portion connected to the lot securing portion and the processing device for reserving the processing device for the processing of the prescribed number of lots secured when the prescribed number of lots are secured. The processing device includes a portion connected to the semiconductor manufacturing system control device for processing the prescribed number of lots for which it is reserved.