Difference of resolution depending on imaging position in one reconstructed image generated in the FFS method is reduced to improve measurement accuracy. The X-ray CT device interpolates missing data of the projection data obtained by the FFS method with view direction interpolation processing using real data of the projection data lining up along the angular direction of the rotational movement, and channel direction interpolation processing using real data of the projection data lining up along the channel direction, and generates a reconstructed image, in which contribution ratios of the projection data having been subjected to the view direction interpolation processing and the projection data having been subjected to the channel direction interpolation processing differ according to position of pixel in the reconstructed image.
