An image processing apparatus (100) for executing a reconstructing process of a tomographic image from a plurality of radiation projection images by using a reconstruction filter, the apparatus comprising: an obtaining unit that obtains the plurality of radiation projection images obtained by detecting X-rays irradiated from a plurality of positions by a digital radiation detector a reconstructing unit that executes the reconstructing process of the tomographic image on the basis of the obtained plurality of radiation projection images and the reconstruction filter and a processing unit that reduces an influence on a first pixel value (q) of a pixel obtained by the reconstruction filter, that influence having been exerted by a second pixel in which a difference between a pixel value of a target pixel of a filtering process in the radiation projection image and a pixel value of a peripheral pixel of the target pixel is larger than a predetermined threshold value in the reconstructing process.
