1. A display device capable of displaying a two-dimensional image and a three-dimensional image, comprising: an image display portion on which a plurality of pixels are arranged in the horizontal and the vertical directions; a video signal control portion which controls the display of each of the pixels arranged on the image display portion; and a polarization control filter which has first polarization regions and second polarization regions, wherein each of the pixels is one of a red pixel, a blue pixel or a green pixel and each of the red, blue, or green pixels includes a first sub-pixel and a second sub-pixel, in which each said first sub-pixel has a first length in one direction and each said second sub-pixel has a second length in the one direction, and in which the first length is shorter than the second length, wherein the first sub-pixels are located at boundaries between the first polarization regions and the second polarization regions, and wherein the video signal control portion controls the pixels when a three-dimensional image is displayed such that (i) the first sub-pixels are displayed in black while an image is displayed by the second sub-pixels, or (ii) the first sub-pixels are not supplied with a display signal while the display signal is supplied to the second sub-pixels.