1. A three dimensional image processing apparatus comprising: a storage unit which stores data of a plurality of images in different radiographing directions; a feature point designation unit which designates, with operation by an operator, at least one feature point on at least two selected images selected from said plurality of images; an operation support unit which generates information for supporting the operation of the operator to designate the feature point; a three dimensional position calculation unit which calculates a three dimensional position associated with the feature point on the basis of a radiographing direction corresponding to the selected image and a two dimensional position of the designated feature point on the selected image; a two dimensional position calculation unit which calculates a two dimensional position of the feature point on an unselected image of said plurality of images on the basis of a radiographing direction corresponding to the unselected image and the calculated three dimensional position of the feature point; a feature point extraction unit which extracts a feature point from the unselected image; a positional shift calculation unit which calculates a positional shift of the two dimensional position of the extracted feature point with respect to the calculated two dimensional position of the feature point; a correction unit which corrects the position of the unselected image on the basis of the calculated positional shift; and an image reconstruction unit which reconstructs a three dimensional image on the basis of the selected image and the corrected unselected image.