PURPOSE: To provide a producing method of a composite reverse osmotic membrane having high water permeability at a relatively low pressure and capable of selectively separating components in a liquid mixture.

CONSTITUTION: A thin film mainly containing a polyamide is formed after applying a water solution containing a compound having ≥2 reactive amino groups on a porous supporting body, allowing an organic solvent containing a multifunctional acid halide to contact with the aq. solution phase to carry out interfacial reaction and just after the interfacial reaction, treating with alcohols to allow the alcohols to react with the unreacted acid halide.