A semiconductor device producing apparatus is disclosed. The apparatus includes a carrier-holding stage for placing a carrier; first, second and third stages each for holding first and second boats one at a time, each boat holding one or more substrates; a boat transfer mechanism for transferring the boats among the first, second and third stages; and a substrate transfer mechanism for transferring the substrate(s) from the carrier to the boat held by the first stage. A controller controls the first stage, the boat transfer mechanism and the substrate transfer mechanism so that the boat transfer mechanism transfers one of the boats from the second stage to the first stage, the substrate transfer mechanism then transfers the substrate(s) from the carrier to the boat held by the first stage, and the first stage then moves the boat into the processing chamber for processing.