A liquid crystal display device with a touch sensor has a liquid crystal display function and a touch sensor function is providing and includes a first substrate including a pixel electrode and a first electrode; a second substrate including a second electrode; and a liquid crystal layer provided between the first substrate and the second substrate. When the liquid crystal display function is activated, the first and second electrodes are supplied with common voltage. When the touch sensor function is activated, the first electrode is applied with a first signal, and the second electrode is configured to receive the first signal to be a second signal as a touch detecting signal.