Abstract: A method for treating a keratin substance or a fiber for a head decoration product, the method including, in the following order, applying a first agent to the keratin substance or the fiber for a head decoration product to form a film, and applying a second agent to the keratin substance or the fiber for a head decoration product on which the film has been formed to remove the film. The first agent contains a component (A): a silicone film-forming agent that is solid at 25° C., and a component (B): an organopolysiloxane other than the component (A), which has a cationic group, and the second agent contains a component (C): an oil agent.