This image processing apparatus identifies the orientation of a document image in a horizontally written text document. The image processing apparatus includes a character identification unit, a line identification unit, and an orientation identification unit. The character identification unit identifies a character bounding rectangle for every character in the document image based on extracted edges. The line identification unit merges the character bounding rectangles identified by the character identification unit to identify a plurality of line bounding rectangles. The orientation identification unit identifies the positions of a short side on one end and a short side on the other end, in the longitudinal direction, of each of the line bounding rectangles identified by the line identification unit to identify the orientation of the document image based on the positional distributions of the identified short sides of the line bounding rectangles.