An image forming apparatus includes an accommodating unit configured to accommodate a recording medium; an image forming unit for forming an image on the recording medium in response to a print job; a reservation unit for designating a portion of the recording medium as a reserved amount and selectively prohibiting use of the reserved amount by the image forming unit; a determining unit for determining whether the print job is a reserved print job or a non-reserved print job; and a authorizing unit for permitting the image forming unit to use the reserved amount for the reserved print job. The reservation unit prohibits use of the reserved amount for the non-reserved print job.