An image forming apparatus including: a conveying unit that conveys a transfer medium; an image forming unit that prints an image on the transfer medium based on an image for printing; and a control unit that receives a detection result of an image detection unit that detects the image printed on the transfer medium, wherein the control unit has a determination function used when an image for which image detection is possible and an image for which image detection is not possible are added to a document image to form the image for printing, the determination function being adapted to exclude an area of the image for which image detection is possible and to determine a state of the printed image based on comparison of information of the detected image and information of the image for printing.