To provide a method which allows the combination of rapid formation of a chemical adsorption film with the preparation of the film which is reduced in the content of impurities and having a dense structure. A method for preparing a chemical adsorption film on the surface of a substrate containing an active hydrogen, characterized in that it includes treating a metal based surfactant having at least one hydrolyzable group with a metal oxide or a partially hydrolyzed product from a metal alkoxide and water in an organic solvent to form a solution, and contacting the solution with the surface of the substrate.