A stereoscopic image display device comprises a frame rate conversion unit that divides 3D input data into left eye image data and right eye image data, inserts reset frame data containing black grayscale data between the left eye image data and the right eye image data, and generates the (n+1)-th frame data to the (n+4)-th frame data containing the left eye image data, the black grayscale data, the right eye image data, respectively, and the black grayscale data, a look-up table that stores local dimming values used to control brightness for the overall local dimming zones to the minimum during the (n+2)-th and (n+4)-th frame periods, and local dimming values used to control brightness for each local dimming zone to target brightness during the (n+1)-th and (n+3)-th frame periods, and a backlight controller that controls light source brightness of the backlight unit for each local dimming zone.