A flexible printed board production method which ensures higher adhesion of copper, excellent workability, easier continuous production and lower costs. The flexible printed board production method comprises the steps of: treating a surface of a polyimide resin film with plasma or short wavelength ultraviolet radiation; activating the treated surface with the use of an alkali metal hydroxide; electrolessly plating the surface of the polyimide resin film with nickel; and electroplating the electrolessly plated surface of the polyimide resin film with copper, whereby a copper layer is formed on the surface of the polyimide resin film.