A line-direction deciding device that can decide the direction of lines in an image having a complicated layout of characters as well as line directions other than vertical and horizontal line directions. The present invention provides a line-direction deciding device that extracts character elements (image components) from an image, examines in which direction the character elements are most densely distributed and decides by majority the direction of lines of characters within a processable area as well as an image inclination correcting device that corrects an image for inclination according to a processing result made by the line-direction deciding device provided with image-inclination detecting means.