An X-ray CT apparatus includes a unit (20) which extracts a high-contrast region of comparatively high X-ray attenuation coefficient from an image and units (21 and 22) which generate an unsharp image concerning the high-contrast region, ON the basis of the position of the extracted high-contrast region and a point spread function peculiar to the apparatus and a unit (23) which subtracts the unsharp image from the original image in order to generate a low-contrast image concerning a low-contrast region of comparatively low X-ray attenuation coefficient.
