1. An obstacle detection apparatus, comprising: a plurality of image input units configured to input images from at least two different camera positions, said plurality of image input units being on a moving object; an image memory configured to store a plurality of images input by said plurality of image input units; an image transformation unit configured to transform one image input by a first image input unit using each of a plurality of transformation parameters each representing a geometrical relationship among a predetermined plane, the first image input unit and a second image input unit, and to generate a plurality of transformed images from a camera position of the second image input unit, each of the plurality of transformed images corresponding to each of the plurality of transformation parameters; a matching processing unit configured to compare each of the plurality of transformed images with another image input by the second image input unit for each area consisting of pixels, and to calculate a coincidence degree of each area between each transformed image and another image; and an obstacle detection unit configured to detect an obstacle area consisting of areas each having a coincidence degree below a threshold from another image.