1. A panoramic image producing apparatus comprising: an intensity image producing means for producing an intensity image of an input image captured by an imaging device; a reference image data storage means for storing a reference image which is used as the reference when the motion of the intensity image is calculated and the absolute motion data of the reference image which represents motion of the reference image from the reference position; a motion data calculation means for setting the intensity image of a newly input image as a target image, calculating the relative motion data of the target image against the reference image, and calculating the absolute motion data of the target image from the reference position using the absolute motion data of the reference image and the relative motion data of the target image; an image stitching means for producing a panoramic image by stitching each input image using its absolute motion data calculated by the motion data calculation means; and a reference image setting means for setting the target image as the new reference image based on a specific condition.