A method and apparatus for reducing image noise, increasing image resolution, and facilitating reduced exposure to a subject to be imaged or improved apparatus life. A radiation tomographic imaging apparatus comprises, as image producing means, inter-imaging-plane filtering processing means for acquiring image data for a plurality of planes generated corresponding to imaging planes that are a plurality of cross-sectional planes of a subject to be imaged, and conducting filtering processing on the image data across the plurality of imaging planes. The filtering processing across the imaging planes that are a plurality of cross-sectional planes facilitates discrimination between a specific shape present in the cross-sectional plane and noise.