PURPOSE: To form thin films with high mass productivity even on substrates which release gases at a high rate by providing a gas emitting chamber for substrates next to a loading and unloading chamber for loading in and out of the substrates and providing a feed mechanism for successively feeding the substrates in said chamber.

CONSTITUTION: A load locking chamber 1 is provided as the loading and unloading chamber which can continuously load in and out the substrates and the substrates are carried via such chamber and a gate valve into the gas emitting chamber 2 provided successively to the chamber 1. The substrates are subjected to gas emission while the substrates are successively fed by the feed mechanism disposed in the chamber 2. The substrates are thereafter passed successively through chambers 3W7 and are subjected to film formation on the surfaces thereof. The substrates after the film formation are taken out of the chamber 1. The volume of the chamber 2 is determined from the time required for the gas emission of the substrates and tact time.