A self-assembled monolayer is formed on the surface of a molded article without roughening the surface of the molded article to thereby perform treatment for preventing a biochemical substance from being adsorbed, for example, on a microchip substrate, and imparting functionality of immobilizing a biofunctional molecule thereto. The surface of a cyclic olefin resin molded article, for example, a microchip substrate, is irradiated with vacuum ultraviolet light having a center wavelength of 172 nm from an excimer lamp to activate a portion serving as a flow channel in the substrate. Next, the molded is immersed in a tank filled, for example, with a fluorine compound solution, and a SAM film that is a self-assembled monolayer is formed on the surface activated by ultraviolet radiation.