1. An image processing apparatus performing a cropping process on a document image containing a text or a graphic, comprising: an extraction section extracting an object area containing the text or the graphic from the document image; a first determination section determining a cropping area surrounding the object area with given margins on the basis of the object area extracted by the extraction section and pre-stored size information of an image; a setting reception section receiving setting of the margins; a second determination section determining the cropping area on the basis of the object area and the received setting of the margins; and a cropping section cropping the cropping area determined by the first determination section or the second determination section from the document image.