1. An X-ray imaging apparatus comprising: an X-ray source configured to irradiate X-rays toward a subject; a filter configured to control a dosage amount of X-rays being irradiated toward the subject; and a processor configured to detect, by identifying a marker formed on an uninterested object, the uninterested object in an X-ray image obtained based on the irradiated X-rays, to set up an uninterested region within the X-ray image based on the detected uninterested object, and to control the filter to set the dosage amount of X-rays to be irradiated into the uninterested region, wherein the processor is further configured to detect the uninterested object in the X-ray image based on pre-stored characteristics of the uninterested object, and to predict a movement of the uninterested object, and to set up the uninterested region based on the predicted movement of the uninterested object, and wherein the marker includes at least one from among a substance which has a higher X-rays penetration characteristic than a surrounding area and a radio-opaque substance.