When generating a tomographic image using a measuring X-ray CT apparatus that is configured to emit X-rays while rotating a specimen that is arranged on a rotary table and reconstruct a projection image thereof to generate a tomographic image of the specimen, an amount of geometric error that is included in the projection image is obtained in advance and stored； the projection image is corrected using the stored amount of geometric error； and a tomographic image is reconstructed using the corrected projection image.
