An image forming apparatus includes a controller, a storage, and a display, and upon output of an image for printing based on print data, the controller stores the print data in the storage and selectively outputs an image for printing, and if the print data includes identification information for identifying the image for printing, the controller outputs the identification information together with the image for printing. In the image forming apparatus, when an image for printing based on print data selected by a user is displayed on the display, the controller restricts an output process so that the image for printing is displayed only if the identification information is not included in the print data.