An X-ray CT apparatus includes a unit for transmitting an X-ray at not less than two different heights of a measurement object and obtaining a given CT image. Alternatively, the X-ray CT apparatus includes a unit for causing an X-ray to pass through the measurement object and obtaining a CT image and a unit for positioning the X-ray source at not less than two different heights of the measurement object, emitting the X-ray, and obtaining the given CT image. Alternatively, the X-ray CT apparatus includes a unit for causing an X-ray to pass through the measurement object and obtaining a CT image and a unit for obtaining CT image data at a third height position between a first and a second height positions based on CT image data of the first and second height positions of the measurement object.