To provide an image forming apparatus that can insert a zonal surplus part between arbitrary pages of a plurality of pages to form images and the image forming method.

The image forming apparatus temporarily memorizes, until receiving the page of the zonal surplus part insertion position (m-th page) specified beforehand, the print data in the received print job in the order of the pages that receives (first page and second page), preferentially rasterises and prints the pages from the page of the zonal surplus part insertion position (m-th page) to the last page (n-th page), when received the zonal surplus part insertion position (m-th page), and prints the page of unprinting that is temporarily memorized (from the first page to the (m-1)-th page) after last page printing.