1. An image processing device comprising: a photographed image acquisition section for sequentially acquiring photographed images of a relatively moving object, the photographed images changing gradually; a characteristic extraction section for extracting characteristic points from a photographed image acquired with the photographed image acquisition section; a characteristic point tracking section for searching a plurality of the photographed images acquired before or after the photographed image from which the characteristic points have been extracted, for candidate corresponding points corresponding to the characteristic points, to keep track of the characteristic points; and a processing section for determining corresponding points from the candidate corresponding points based on tracking results to calculate coordinates of a photographing position or the object using the determined corresponding points.