An image processing apparatus, includes: an acceptance unit that accepts image data and reading data; an extraction unit that extracts rectangular images by segmenting one image of the image data and the reading data; a first searching unit that selects at least one of the rectangular images extracted by the extraction unit, set a search range calculated from the error, searches for a matching position of the selected rectangular image in the other image of the image data and the reading data; an estimation unit that estimates a matching position of a rectangular image in the other image on the basis of the matching position of the selected rectangular image in the other image; and a second searching unit that searches for a matching position of the other rectangular image in the other image using the matching position estimated by the estimation unit as a reference.