An X-ray CT system of an embodiment includes an X-ray scanner including an X-ray generator that performs X-ray imaging by scanning around a subject that is placed on a bed top and an X-ray detector. The X-ray scanner performs X-ray imaging while the bed top and the X-ray scanner are being reciprocated relative to each other in a first direction along the longitudinal direction of the bed top and a second direction opposite thereto. The X-ray CT system further includes a comparator that compares the positions of the bed top when a predetermined number of views are acquired in a plurality of times of X-ray imaging in the first direction or in a plurality of times of X-ray imaging in the second direction.
