A film forming apparatus includes a rotary table having a loading area at a first surface side thereof and revolving a substrate loaded on the loading area, a rotation mechanism rotating the loading area such that the substrate rotates around its axis, a processing gas supply mechanism supplying a processing gas to a processing gas supply area so that a thin film is formed on the substrate which repeatedly passes through the processing gas supply area the revolution of the substrate, and a control part configured to perform a calculation of a rotation speed of the substrate based on a parameter including a rotation speed of the rotary table to allow an orientation of the substrate to be changed whenever the substrate is positioned in the processing gas supply area, and to output a control signal for rotating the substrate at a calculated rotation speed.