A film forming apparatus that produces a thin film by repeating cycles of sequentially supplying reaction gases including a loading table in a vacuum vessel having substrate mounting areas; reaction gas supplying units arranged in a peripheral direction with intervals to supply the reaction gases onto substrates; separating areas separating atmospheres of the processing areas; separation gas supplying units supplying separation gases to render a supply amount to outer peripheral side separation areas greater than a supply amount to center side separation areas; a ceiling face surrounding narrow areas together with the loading table to enable the separation gases flow from the separating areas to the processing areas along the center side separation areas and the outer peripheral side separation areas a vacuum ejecting mechanism; and a rotary mechanism rotating the loading table relative to the reaction gas supplying units and the separating areas.