STORAGE SYSTEM

A storage system useful for processing large amounts of data is provided.When a wafer cassette to be accessed that includes a first semiconductor wafer is not connected to a slot of a host apparatus and is stored in a wafer cassette stocker, the host apparatus causes a wafer cassette transport device to transport the wafer cassette to be accessed, to the slot of the host apparatus, and to connect it thereto. When the wafer cassette to be accessed is not connected to the slot of the host apparatus and is not stored in the wafer cassette stocker, the host apparatus causes a wafer transport device to transport the first semiconductor wafer from a wafer stocker to a cassetter, causes the cassetter to accommodate the first semiconductor wafer in a cassette case and causes the wafer cassette transport device to transport a wafer cassette to be accessed including the first semiconductor wafer to the slot of the host apparatus, and to connect it thereto.