A stereoscopic image display includes a display panel; a polarization control panel that is positioned on the display panel and controls the polarization direction of light incident from the display panel; a lens panel positioned on the polarization control panel and having a plurality of lens shaping portions; a first driver for driving the display panel; a second driver for supplying a driving voltage to the polarization control panel; a timing controller for controlling the first driver and the second driver; and a sensing unit that senses the driving voltage supplied to the polarization control panel and outputs a decision signal for deciding whether the sensed driving voltage is in normal condition or abnormal condition.