1. A range finder comprising: a projector for projecting a coded stripe pattern; a first camera for picking up an image of the stripe pattern projected by the projector, the first camera placed so that a principal point of the first camera and a principal point of the projector are placed along a length direction of the stripe pattern; and a second camera for picking up an image of the stripe pattern projected by the projector, the second camera placed so that a principal point of the second camera and the principal point of the first camera are placed away from each other in a direction being not parallel to the length direction of the stripe pattern, wherein: an area with change amount of the stripe pattern, which is picked up by the first camera, with respect to the stripe pattern projected by the projector being a predetermined value or more is determined; a new code is assigned to the area; the second camera picks up a recoded stripe pattern projected by the projector after the new code is assigned; and range information of a three-dimensional object onto which the stripe pattern is projected is generated based on the recoded stripe pattern picked up by the second camera.