The present invention herein provide a thin film-manufacturing device and a thin film-manufacturing method which are excellent in the mass-production ability and productivity, which permit the stable and continuous production of films over a long period of time while reproducing a good film thickness distribution, a good compositional distribution and a high film-forming rate and controlling the number of particles generated during the film-formation to a lower level. The device is one serving as a CVD device in which a film-forming gas is introduced into a reaction chamber from the upper portion of the chamber serving as a reaction space, through a shower head and a film is formed on a heated substrate, wherein the device is so designed that the upper reaction space is constructed by the substrate-supporting stage which is free of any rotational motion or free of any elevating motion, the shower head and a deposition-inhibitory plate, that the substrate-supporting stage and the deposition-inhibitory plate are so arranged as to form, between them, a concentric gap or interstice serving as a gas-exhaust path through which an inert gas can flow from the upper portion of the gas-exhaust path along the deposition-inhibitory plate and that a lower space is formed on the secondary side of the gas-exhaust path.