A film forming apparatus for forming a polyimide film on a substrate installed within a film forming container. The apparatus includes: a first vaporizer configured to vaporize a first raw material in a solid state, and supply the vaporized first raw material gas to the substrate; a second vaporizer configured to vaporize a second raw material in a liquid state, and supply the vaporized second raw material gas to the substrate; a first pressure measurement unit configured to measure the internal pressure of the first vaporizer; a second pressure measurement unit configured to measure the internal pressure of the second vaporizer; and a controller configured to calculate a supply amount of the first and second raw material gases by the first and second pressure measurement units, respectively, and control the first and second vaporizers to supply the first and second raw material gases in a uniform amount.