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, the photographed image acquisition section including or communicating with a photographing device for photographing the series of photographed images; 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 determining orientation of the photographing device using a corresponding feature points and for performing a 3D measurement to measure 3D coordinates of the corresponding feature points using the 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; 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; an erroneous corresponding point deletion section for deleting corresponding feature points determined as inappropriate by the corresponding point appropriateness determination section; and an allowable range setting section for setting an overlapping area of the three or more error ranges of the 3D coordinates, for an identical point on the object, obtained from different stereo images as an allowable range of the 3D coordinates; wherein the corresponding point appropriateness determination section determines those corresponding feature points in the stereo images used to measure the 3D coordinates without an overlapping area between the error range and the allowable range as inappropriate, wherein the error range is calculated as a function of a baseline length, a photographing distance, a focal length and a pixel size.