A substrate treatment apparatus which uniformly forms a fine resist pattern with a desired dimension within a plane of a substrate is disclosed. In a solvent vapor supply unit, a solvent vapor discharge nozzle is provided which can discharge a solvent vapor for swelling a resist pattern while moving above the front surface of a wafer. The wafer for which developing treatment has been finished and on which a resist pattern has been formed is carried into the solvent vapor supply unit, and the solvent vapor discharge nozzle is moved above the front surface of the wafer, so that the solvent vapor discharge nozzle supplies the solvent vapor onto the front surface of the wafer. This uniformly supplies a predetermined amount of solvent vapor to the resist pattern on the front surface of the wafer. As a result, the solvent vapor causes the resist pattern to evenly swell by a predetermined dimension, so that a resist pattern with a desired dimension is finally uniformly formed within the plane of the wafer.