A stereoscopic image display includes a display panel, which selectively displays a 2D image and a 3D image and includes a plurality of pixels, and a patterned retarder for dividing light from the display panel into first polarized light and second polarized light. Each of the pixels includes a main display unit including a first pixel electrode and a first common electrode, a subsidiary display unit including a second pixel electrode and a second common electrode, and a line unit disposed between the main display unit and the subsidiary display unit. The line unit includes a gate line, a discharge control line through which a discharge control voltage is applied to a discharge control TFT, and a lower common line through which a common voltage is applied to an upper common line.