The surface of fine pigment particles is efficiently treated using low energy without causing a cost increase. Provided is a method of treating the surface of fine pigment particles, characterized by maintaining a small gap of 1 mm or narrower between two treating surfaces which are able to get close to and apart from each other and relatively rotate and using the gap between the two treating surfaces which is kept so narrow, as a passage for a fluid to be treated, thereby forming a thin film of the fluid to be treated (forced thin film) . Fine pigment particles are formed in this thin-film fluid (forced thin film) . The method is further characterized by modifying the surface of the formed fine pigment particles within the thin-film fluid (forced thin film).