A stereoscopic image display includes a display panel which includes a plurality of pixels each including a main display unit and an auxiliary display unit, is divided into a first screen block and a second screen block, and includes a first discharge control line connected to auxiliary display units of the first screen block and a second discharge control line connected to auxiliary display units of the second screen block, a control voltage generator which generates a first discharge control voltage of a first AC waveform and a second discharge control voltage of a second AC waveform, of which a phase is later than a phase of the first AC waveform by a half frame period, and a control voltage delay unit which delays the first and second discharge control voltages.