An image forming apparatus has a printing unit for executing a single-sided print job and a double-sided print job. A storage unit stores print target data as backing sheet image data when a single-sided print job is executed. An image reading unit reads images on both sides of a document that is subjected to image processing. A backing sheet judgment unit judges whether there is an image that matches a backing sheet image among the images on both sides of the document by comparing the document image data read by the image reading unit with the backing sheet image data stored in the storage unit. An exclusion processing unit performs processing to exclude from the image processing targets an image judged by the backing sheet judgment unit to match the backing sheet image among the images on both sides of the document read by the image reading unit.