1. A stereo image matching apparatus, comprising: a window image extraction unit for extracting window images, each having a predetermined size around a selected pixel, for individual pixels of images that constitute stereo images captured by two or more cameras synchronized with one another; a local support-area determination unit for extracting a similarity mask having similarities equal to or greater than a threshold and a local support-area mask having neighbor connections to a center pixel of the similarity mask, from each of similarity images generated depending on differences in similarity between pixels of the window images; a similarity extraction unit for calculating a local support-area similarity from a sum of similarities of a local support-area determined by the local support-area mask; and a disparity selection unit for selecting a pair of window images for which the local support-area similarity is maximized, from among the window images, and then determining a disparity for the stereo images.