An image forming apparatus automatically identifying top and bottom of document image based on characteristics with regard to shapes or positions of data, etc. recorded on document. Distribution states of pixel cumulative values in main scanning direction and sub scanning direction of image signals provided by scanning the document, are analyzed and top and bottom of the document image is identified from the result of analysis. Further, it is possible to identify the top and bottom of the document image by analyzing the distribution states the pixel cumulative values in the main scanning direction and the sub scanning direction of the image signals and identifying letter series regions and line segment regions displaced therefrom. In addition thereto, it is possible to automatically identify the top and bottom of the document image based on distribution states in the main scanning direction and the sub scanning direction of specific signs included in the image signals provided by scanning the document or distribution states of pixel cumulative values of specific image regions including the specific signs.