1. A position detection apparatus that detects the position of a moving object, said position detection apparatus comprising: an image acquisition device that acquires an image of the forward field of view of said moving object, a distance image acquisition device having the same field of view as said image acquisition device that acquires a distance image simultaneous to acquisition of an image by said image acquisition device, a characteristic point extraction device that extracts respective characteristic points from the images of at least two consecutive frames, and a reference characteristic point selection device that calculates the amount of displacement of a position between two frames of a characteristic point extracted by said characteristic point extraction device based on said distance image, and selects a reference characteristic point for calculating position according to said amount of displacement.