A liquid crystal display capable of changing the luminance of backlight according to external illumination is provided to simplify area and configuration of a sensing circuit by omitting a storage device. An LCD panel includes a plurality of liquid crystal cells segmented by a black matrix. A backlight(70) irradiates the light in the rear side of the LCD panel. According to the illumination of the external light which is income in the display surface of the LCD panel, an external light sensing circuit differently controls the brightness of the back light. A first sensor unit reacts to panel temperature. A second sensor part reacts to the panel temperature and external light. A buffer unit diversifies the voltage of the output node as the amount of voltage change of the input node. A voltage distributor determines the initial voltage value of the output node.
