An area of an extraneous substance (e.g. area of metal or the like) in images (pre-interpolation projection data in the embodiment) of the extraneous substance (e.g. high-density substance such as metal) extracted and separated by extraction separation in step S1 is interpolated by area interpolation in step S2. Therefore, artifacts can be reduced, while maintaining high spatial resolution, if tomographic images (first tomographic images in the embodiment) are generated by first tomographic image generation in step S3 from the interpolation images interpolated and generated (post-interpolating projection data in the embodiment).
