A film forming apparatus is provided that can prevent source gases from reacting together before reaching the substrate being processed in the apparatus, minimize the influence of the radiation heat from the substrate, and make the gas behavior in the reaction chamber better for crystal film formation. The apparatus forms a film on a surface of a heated substrate 5 by causing a first source gas and a second source gas to react together. The apparatus has a processing chamber 1, in which the substrate 5 is placed. The processing chamber 1 is divided into a heating chamber 1a and a reaction chamber 1b by at least the substrate 5 so that the substrate surface can be exposed to the source gases in the reaction chamber 1b. The apparatus further has an exhaust duct 7, through which the exhaust gas can be discharged. The exhaust duct 7 faces the exposed substrate surface and connects with the reaction chamber 1b. The apparatus further has first supply ports 11 and second supply ports 12, through which the first and second source gases respectively can be supplied independently onto the substrate surface. The supply ports 11 and 12 are positioned outside the exhaust duct 7. This enables the source gases to react immediately near the substrate 5 so that high-quality crystal film formation can be performed on the substrate.