A position measurement device is provided that can precisely measure the photographing position or posture of a photographing device or the coordinates of an object based on sequentially changing photographed images. A position measuring device 100 of the invention comprises: an image acquisition section 2 for acquiring a series of photographed images changing continuously or little by little along with position displacement relative to an object to be photographed; a positional relationship measurement section 9 for measuring position displacement and posture change of the image acquisition section 2; a feature extraction section 3 for extracting feature points from the photographed images obtained with the image acquisition section 2; a feature point tracking section 4 for tracking the feature points by searching corresponding points corresponding to the feature points on a plurality of the photographed images; an image selection section 61 for selecting an image to be processed from the series of photographed images based on a measurement result made with the positional relationship measurement section 9; and a position measurement section 7 for measuring the photographing position and the photographing posture of the image acquisition section 2 based on the image to be processed selected with the image selection section 61.