A substrate processing system which sprays exposure process gas onto a substrate disposed within a chamber. The substrate processing system is used, for example, for performing an exposure process of an organic film formed on a substrate in a gas atmosphere obtained by vaporizing an organic solvent solution for dissolving and reflowing an organic film. The substrate processing system comprises: the chamber having at least one gas inlet and at least one gas outlets; a gas introducing means which introduces the exposure process gas into the chamber via the gas inlet; and a gas distributing means. The gas distributing means separates an inner space of the chamber into a first space into which the exposure process gas is introduced via the gas inlet and a second space in which the substrate is disposed. The gas distributing means has a plurality of openings via which the first space and the second space communicate with each other and introduces the exposure process gas introduced into the first space into the second space via the openings.