An apparatus is provided for controlling an X-ray radiation field of an X-ray imaging apparatus including an X-ray generator and an X-ray detector arranged opposite to the X-ray generator. The apparatus includes a light-emitting unit configured to emit light and disposed adjacent to one of the X-ray generator and the X-ray detector, a light-receiving unit configured to detect the light emitted by the light-emitting unit and disposed adjacent to the other one of the X-ray generator and the X-ray detector, a radiation field setter configured to set an X-ray radiation field based on the detected light, and an X-ray driver configured to control driving of the X-ray generation units which correspond to the set X-ray radiation field, to emit an X-ray.
