An X-ray CT photographic apparatus including: a beam shaping mechanism that regulates an irradiation range of an X-ray generated from an X-ray generator and shapes the X-ray into an X-ray cone beam; and a main body controller that changes a read region, where an X-ray detection signal is read in the X-ray detector, according to the irradiation range of the X-ray cone beam. The main body controller changes the irradiation range of the X-ray cone beam to an x-axis direction during an X-ray CT photography such that only a set CT photographic region is irradiated with the X-ray cone beam according to the set CT photographic region input through a CT photographic region setting unit. The main body controller changes a read region in an X-ray detector with respect to the x-axis direction in a detection surface of the X-ray detector during the X-ray CT photography.