In a 3D image display device and a driving method thereof, a left-eye image and a right-eye image are displayed at a 3D display frequency higher than a 2D display frequency in a 3D mode. The left-eye image or the right-eye image is applied to a data line as data voltages having the same polarity and the same magnitude throughout at least two consecutive frames. A gate-on voltage is applied to a plurality of gate lines crossing the data line sequentially at an interval of a compensation gate-on application time calculated based on a total data delay value.