PURPOSE: To falsely inform a difference in colors on an original to an operator based upon a printing result even when a printing part for printing out data only by one color is used.

CONSTITUTION: An image processing part 2 is connected to the output side of a reading part 1 for reading out color image data at least consisting of a basic color and a color other than the basic color, a printing part 3 for printing out data at least by one color is connected to the output side of the image processing part 2 and the processing part 2 is executes image processing so that basic color image data read out by the reading part 1 and the color image data other than the basic color are visually distinguished and printed out by the printing part 3. When the color image data obtained by the processing part 2 is printed out by the printing part 3, the operator can easily confirm the distinction of the basic color from the color other than the basic color on a printing result.