1. An apparatus for compressing three-dimensional stereoscopic images, comprising: two image input units for outputting first and second images corresponding to images of one object; a difference estimator for searching for an overlapped image having the smallest disparity by comparing the first image with a search area in which a boundary part of the second image is extended, and for acquiring a residual image between the first image and the overlapped image whose position is arranged after computing and storing a position difference between the overlapped image and the second image; and an encoder for encoding the residual image and the position difference output from the difference estimator and the first image output from one of the image input units.