When an information medium is copied, information is printed while preventing personal information from leaking. An image scanning section 2 scans the information medium and inputs the image. An identification section 64 calculates the size of the information medium from the inputted image and identifies the type of the information medium. The position of the unique image indicating personal information is fixed according to the information medium. An area determination section 63 identifies the unique image in the information medium and determines the position of the specific area in which the unique image exists in the inputted image. A control section 7 performs image processing for masking the specific area. An image forming section 3 prints the image in a state in which the unique image is hidden.