Abstract: This invention provides a process for accumulating different organic molecular films on oxidized III-V-group compound semiconductor substrates in order to produce a stable, high-quality organic monomolecular film that is three-dimensionally regularly arranged, as well as a process for producing a fine pattern of such organic films. This organic film is formed by immersing a III-V group compound semiconductor substrates in a vessel containing a solution containing phosphonic acid dissolved into a solvent in order to form a self-assembled film, and placing the substrate into a different solution to adsorb metal ions to the surface of the film, or immersing the substrate in a bromide or an acid or alkali solution to denature functional groups, then immersing it in a solution containing organic molecules that are selectively chemically adsorbed to the modified functional groups.