An apparatus and method for displaying a three-dimensional (3D) image are provided. The apparatus includes an image correction unit which separates R, G, and B unit frame images from an input unit frame image and converts lines of each of the R, G, and B unit frame images into lines of black pixels; a display panel which sequentially outputs the R, G, and B unit frame images each having the lines of black pixels; and a polarizing element which outputs the R, G, and B unit frame images output by the display panel as left- and right-eye images for a user by polarizing on one side of each of the lines of black pixels in each of the R, G, and B unit frame images differently from the other side of each of the lines of black pixels in each of the R, G, and B unit frame images.