1. A measurement device comprising: an image pickup portion mounted in a mobile unit that outputs a plurality of images that are taken with a first view angle and that contain a measurement object and a plurality of images that are taken with a second view angle smaller than the first view angle and that contain the measurement object; a retrieval portion that retrieves, from at least two images taken with the second view angle by the image pickup portion, points that are each a feature point on the measurement object and that are in correspondence between the at least two images taken with the second view angle; a position and posture calculation portion that, on a basis of the plurality of images taken with the first view angle by the image pickup portion, calculates a relative relationship of a position and a posture of the image pickup portion occurring at each of times of image-taking of the plurality of images taken with the first view angle; a position and posture estimation portion that, on a basis of the relative relationships of the positions and the postures calculated by the position and posture calculation portion, estimates the relative relationships of the positions and the postures of the image pickup portion occurring at the times of image-taking of the at least two images with the second view angle; and a position measurement portion that measures a three-dimensional position of the points retrieved by the retrieval portion, on a basis of the retrieved points and the relative relationships of the positions and the postures estimated by the position and posture estimation portion.