1. An image processing device comprising: a photographed image acquisition section for acquiring a series of sequentially photographed images of a relatively moving object where three or more adjacent images have an overlapping area with each other; a feature extraction section for extracting feature points from any of the sequentially photographed images; a feature point tracking section for tracking and correlating the feature points for the series of photographed images; a stereo image selection section for selecting stereo images from the series of photographed images, the stereo images being a pair of images; an orientation process/three-dimensional (3D) measurement section for performing an orientation and a 3D measurement using corresponding feature points, the corresponding feature points being the feature points correlated in the stereo images selected by the stereo image selection section; an error range calculation section for calculating an error range of 3D coordinates of the corresponding feature points obtained from the stereo images in the 3D measurement; a corresponding point appropriateness determination section for determining whether or not the corresponding feature points are appropriate for 3D measurement based on the error range of the 3D coordinates of the corresponding feature points calculated by the error range calculation section; and an erroneous corresponding point deletion section for deleting corresponding feature points determined as inappropriate by the corresponding point appropriateness determination section.