An apparatus and a method of displaying 3-Dimensional image are disclosed. A camera unit serves to capture an image of a viewer. A position tracking device serves to detect a position of the viewer using a video frame included in the captured image and calculate a position of a non-transmissive region of a 3D image filter based on the detected position of the viewer. A display unit serves to move the non-transmissive region of the 3D image filter according to the calculated position of the non-transmissive region. Changing a sweet spot of the 3D image to suit movement of the viewer has the effects of enlarge a viewing angle of the viewer and preventing crosstalk and image flipping even when the viewer moves.