There is provided an image processing apparatus where in an additional image storage unit 3, a color additional image is stored into a color image storage unit 4, and a black/white additional image is stored into a black/white image storage unit 5. A color judging unit 2 judges as to whether an input image corresponds to a color image, or a black/white image every page thereof. Based upon the judgment result of the color judging unit 2, an image synthesizing unit 6 adds the color additional image stored in the color image storage unit 4 to the input image when the input image is the color image, and adds the black/white additional image stored in the black/white image storage unit 5 in the input image when the input image is the black/white image. Then, the image synthesizing unit 6 outputs the resulting image synthesized with the additional image. When the input image is the black/white image, the black/white additional image is added to this input image charge amount for the black/white image can be determined.