To allow a substrate of decreased size to be stored in a substrate housing device (hoop) constituting a transportation system corresponding to a large-diameter substrate.

An attachment for a substrate of different diameter includes an upper plate 401 and a lower plate 402 supported by a first support groove 16e capable of supporting an eight-inch wafer, and holding posts 403a-403c which are provided to the upper plate 401 and the lower plate 402 and contain a second support groove 404 capable of supporting a wafer 14, being a two-inch wafer (by way of a wafer holder 100 and a holder member 405 as require). The wafer 14 which is a two-inch wafer can be stored in a pod 16 corresponding to an eight-inch wafer, for sharing the pod 16 which is a transportation system, resulting in reduced cost of a semiconductor manufacturing apparatus. Gas supply nozzles are set away from the wafers 14, so that the reactive gas is sufficiently mixed before reaching the wafers 14, resulting in improved film-forming precision on the wafers 14.