By enabling the confirmation of a finish state by a preview reliably, it makes it possible to prevent unnecessary image formation processing due to setting errors by a user. Finish state information showing a finish state of paper is simultaneously displayed in addition to a preview image showing an entire page of image data on a preview screen before performing image formation. The finish state information is displayed, for example, as "2-sided: Front 1" showing to be the first page in 2-sided printing. In addition thereto, an icon showing to be a front side in 2-sided printing is displayed at the same time. This display allows the user to recognize that a setting of 2-sided printing is performed and image data of the current preview image is the front side of the first page in the 2-sided printing.