A stereoscopic image display device includes a display panel including a plurality of pixels, a scan driver, a gate driver, a data driver, and a controller, and a sub-frame includes a first period during which a data voltage according to an image data signal emitted in the previous sub-frame is initialized, a second period during which a data voltage according to the image data signal written in the previous sub-frame is transmitted and a threshold voltage of a driving transistor of each pixel is compensated, a third period during which a data voltage according to a next sub-frame's data signal is sequentially written to the respective pixels, and a fourth period that is concurrent with and equal to or longer than the third period and during which the respective pixels concurrently emit light corresponding to the data voltage according to the image data signal written in the previous sub-frame.