Provided is an image forming apparatus which displays display information regarding product liability, which is read out from a storage medium of a processing unit, the image forming apparatus carrying out judgment as to whether or not the processing unit is a genuine/recommended product based on the information read out from the storage medium. The image forming apparatus carries out a series of image forming process when the processing unit is a genuine or a recommended product. On the other hand, when the processing unit is an unauthorized product, the image forming apparatus displays the display information and/or the comparison result. On this account, the user can easily and securely confirm display information regarding product liability of the processing unit, and/or information regarding compatibility of the processing unit with the image forming apparatus, while ensuring superior security and reliability.
