A liquid crystal display device (1) includes: a liquid crystal display panel (10) in which a liquid crystal layer (13) is provided between an active matrix substrate (11) and a counter substrate (12); and a backlight (20) which emits light toward the liquid crystal display panel (10). A peripheral region (R2) which is on a periphery of an image display region (R1) includes light sensors [16 (16a and 16b)] for detecting an external brightness of the liquid crystal display device (1). Light emitted from the backlight (20) has a transmittance of not more than a transmittance obtained during black display in the peripheral region (R2) in which the light sensors are provided, while the light sensors are detecting an external brightness of the liquid crystal display device (1). This allows a realization of a liquid crystal display device including light sensors which are less affected by stray light and are capable of detecting external light with higher accuracy.