1. An image position matching apparatus comprising: a position matching means for matching the positions of two images obtained of the same subject, wherein said two images consist of a two-dimensional transparency image and a three-dimensional transparency image, and the position matching means forms a two-dimensional projection image, which has a high degree of correlation to the two-dimensional transparency image, from the three-dimensional transparency image and matches the positions of said formed two-dimensional projection image and the two-dimensional transparency image.