A liquid crystal display device is adapted to reduce cross-talk and signal noise so as to improve the perception ratio and accuracy of a sense element. The liquid crystal display device includes: a liquid crystal panel including a plurality of pixels connected to gate lines and data lines thereon, respectively; a gate drive circuit applying scan signals to the gate lines; a data drive circuit applying pixel voltage signals to the data lines; at least one sensor unit formed in at least one pixel region and sensing external lights and a touch of the liquid crystal panel; a switch unit switching a switch voltage and the pixel voltage signals to be applied to the data lines on the liquid crystal panel; a sense processor processing the sensed signal from the sensor unit; and a timing controller controlling the gate drive circuit, the data drive circuit, the switch unit, and the sense processor to be driven in one of data write mode and light sense mode.