A stereoscopic image display device including a display panel including a plurality of sub-pixels arranged in a matrix defined by a horizontal direction and a vertical direction, the display panel having a changeable display direction; and a parallax unit on the display panel and including a plurality of optical elements having a tilt angle of 30° to 60° relative to the vertical direction and a pitch corresponding to a multiple of a pitch of the sub-pixels. Among the sub-pixels located to correspond to each of the optical elements, at least two sub-pixels, adjacently arranged, display the same view image.