The X-ray tube disclosed herein includes an electron emission unit including an electron emission element using a cold cathode; an anode unit disposed opposite to the electron emission unit, with which electrons emitted from the electron emission unit collide; and a focus structure disposed between the electron emission unit and a target unit disposed on a surface of the anode unit that is opposed to the electron emission unit. The electron emission unit is divided into a first region and a second region which can independently be turned ON/OFF. The X-ray tube is focus-designed such that collision regions, at the anode unit, of electron beams emitted from the respective first region and second region substantially coincide with each other.