A stereoscopic image display device comprises: a display panel including thin film transistors (TFTs) formed at crossings of data lines and gate lines and m×n (m and n are positive integers) number of pixels divided into main subpixels and auxiliary subpixels; a data driving circuit supplying a data voltage of a two-dimensional (2D) image to the data lines in a 2D mode and supplying a data voltage of a three-dimensional (3D) image to the data lines in a 3D mode; and a gate driving circuit simultaneously supplying gate pulses to a pair of gate lines including neighboring gate lines in the 2D mode and simultaneously supplying gate pulses to even-numbered gate lines in the 3D mode.