An X-ray CT measuring apparatus configured to emit an X-ray from an X-ray source while rotating a subject arranged on a rotary table, and obtain a tomographic image of the subject by reconstructing projection images, includes an X-ray fluctuation calibration jig arranged in an X-ray field of view, a detection unit configured to detect fluctuations in an X-ray focal position by using an X-ray projected image of the X-ray fluctuation calibration jig, and a correction unit configured to correct an X-ray projection image of the subject by using the detected fluctuations in the X-ray focal position.
