There is provided a film forming apparatus including gas supply paths, retaining units, valves, a purge gas supply unit and a control unit. The control unit is configured to implements a film forming process for sequentially performing operations of actuating the valves such that reaction gases are retained in the retaining units, the internal pressures of the retaining units are increased and then the reaction gases are supplied from the retaining units into the process chamber, and a purging process for subsequently repeating, a plurality number of times, operations of actuating the valves such that the purge gas is retained in the retaining units, the internal pressures of the retaining units are increased to a pressure higher than the internal pressures of the retaining units which is increased in the film forming process, and then the purge gas is supplied from the retaining units into the process chamber.