To allow fog removal even in a densely foggy image. A fog density calculating unit 11 calculates the fog density of an input image given, by using a separated illumination light component. A reflectance component fog removing unit 13 performs fog removal on a reflectance component calculated by a reflectance calculating unit. An illumination light component fog removing unit 14 performs fog removal on the separated illumination light component. Here, the degree of fog removal by the reflectance component fog removing unit 13 is higher than the degree of fog removal by the illumination light component fog removing unit 14. Thereby, the degree of fog removal of the reflectance component can be raised without significantly raising the level of fog removal of the illumination light component.