1. A range finder comprising: a projector unit for projecting linearly polarized light onto a subject; at least one image input unit disposed in a position different in principal point from the projector unit; and a polarizing direction selection unit for selecting light having a polarizing direction from light reflected by the subject, wherein the at least one image input unit captures a reflected image based on the light selected by the polarizing direction selection unit from the light reflected by the subject and measures a 3D shape of the subject on the basis of the reflected image.