In a liquid crystal display including a liquid crystal display panel formed by sandwiching a liquid crystal layer between an active matrix substrate and an opposed substrate, and a backlight that illuminates the liquid crystal display panel from a side of the active matrix substrate, a first optical sensor and a second optical sensor are disposed in a peripheral region on a glass substrate of the active matrix substrate. The first optical sensor is formed so that light external to the liquid crystal display and light propagating inside the active matrix substrate enter the first optical sensor. The second optical sensor is formed so that only light propagating inside the active matrix substrate enters the second optical sensor. Also, the second optical sensor is shielded from the external light. For example, a light-shielding film is formed on an upper surface of the second optical sensor.