To output even a document image, which is fetched while being inclined, in the original state or fixed state.

A circumscribed rectangle surrounding a character for the unit of one character is extracted from a document fetched by a scanner or the like. A circumscribed rectangle 1a for punctuation marks is extracted as the one sufficiently smaller than a circumscribed rectangle 1 for ordinary characters and further, the position in respect to that circumscribed rectangle 1 for ordinary characters is changed according to whether a document is written laterally or longitudinally and the inclination angle of the fetched document image. The position of blank at the time of starting a new line for the document in the middle of line is similarly changed as well. An inclination detecting part detects the inclination angle of the fetched document image from the circumscribed rectangle 1 and temporarily discriminates whether the document is written laterally or longitudinally from that detected angle. A document direction discriminating part discriminates the document direction from the result of that temporary discrimination, the position of small circumscribed rectangle showing the punctuation marks and the position of blank and determines a correction angle. Based on the inclination angle detected by the inclination detecting part and the correction angle determined by the document direction discriminating part, the inclination angle of the fetched document image is corrected and the document direction is corrected.