Position measurement apparatus for measuring position of object having reflective surface in the three-dimensional space

A storage device stores capturing conditions including a viewpoint position and a shooting direction of the camera, model data including a shape of a segmented mirror, and feature point data representing a positional relationship among a viewpoint position and feature points. A camera captures the segmented mirror having a reflective surface to obtain a captured image including at least a part of the reflective surface. A marker object has feature points, and is fixed at a predetermined position with respect to the camera. A feature-point extracting unit extracts multiple feature points from a captured image in which the feature points are reflected in the reflective surface, and determines positions of the feature points within the captured image. A position measuring unit calculates a position of the segmented mirror, based on the capturing conditions, the model data, the feature point data, and the positions of the feature points within the captured image.