We discuss the light leakage issue of LCD due to stress to the polarizer from the backlight temperature. To detect light leakage, we measured black luminance and low gray scale curves by backlight running time. The result shows that gray scale curve's change at upper side of light leakage shift up and that of right and left side shift down. These phenomena are similar to phenomenon from variation of WV-TAC axis. To discuss this result, we insist the heated part of polarizer must be expanded. Finally, our experiment result by changing rubbing angle of cell shows improvement of light leakage.