Provided is an X-ray imaging apparatus which includes a collimator configured to adjust an irradiation range of an X-ray irradiated from the X-ray source. The collimator comprises a first field size range adjustor comprising a first plurality of blades and a driving power transfer unit configured to transfer driving power to the first plurality of blades, a second field size range adjustor facing the first field size range adjustor and comprising a first plurality of blades, and a connector configured to respectively connect the first plurality of blades of the first field size range adjustor to the first plurality of blades of the second field size range adjustor so as to make the first plurality of blades of the second field size range adjustor move as the first plurality of blades of the first field size range adjustor move.