In a 3D image display apparatus, a display unit includes a plurality of pixels and alternately displays a left-eye image in a first group of the pixels and a right-eye image in a second group of the pixels along a first direction, a barrier unit includes a light blocking portion blocking light received from the display unit and a light transmitting portion transmitting the light received from the display unit, and the light blocking portion and the light transmitting portion are alternately arranged in the first direction. A position information extraction unit determines the distance between the display unit and a viewer watching the display unit, and a control unit controls the display unit and the barrier unit in accordance with the distance information to allow the display unit and the barrier unit to be operated in a first mode or a second mode. Thus, a distance range in which the viewer perceives the 3D image increases.