According to this invention, bookbinding data containing pages created by respective applications can be constructed regardless of the type of application. Even when one or more desired pages contained in bookbinding data are selected, image editing is designated, but a non-image page exists in the selected pages, the non-image page can be excluded from editing targets, and the process can shift to image editing. For this purpose, when a plurality of pages are selected and image editing is designated, whether each selected page is an editable image page is determined. An editable page is temporarily stored. After all the selected pages are determined, an image editing application is activated to edit stored editable image pages.