An X-ray apparatus includes an X-ray source configured to radiate X-rays, a collimator configured to adjust a radiation field of the X-rays and rotate on an optical axis direction of the X-rays, a ring-shaped first rotation transfer unit centered on an optical axis of the X-rays in the X-ray source, a second rotation transfer unit interlocked with the ring-shaped first rotation transfer unit and configured to rotate as the collimator rotates, a rotation sensor configured to sense an amount of rotation of the second rotation transfer unit, and a detector comprising a receiving surface on which the X-rays radiated from the collimator are incident.
