A liquid crystal display device with improved thermal exhaustion property, enabling a thickness reduction, includes a backlight including light sources illuminating a liquid crystal panel from a back face, and a chassis holding the backlight. The backlight includes: plural light-source units each including a combination of a LED emitting light in a direction parallel to a display surface of the panel, a wiring board mounted with the LED, and a light-guide plate having translucency for guiding the LED light toward the panel; a metal chassis supporting the light-source units; and a thermally conductive sheet tightly inserted between the metal chassis and a reverse side of the wiring board opposite to the LED-mounted face. A wiring pattern is formed on the reverse side. The metal chassis and the wiring pattern located within a predetermined distance of the LED outer periphery are connected through the thermally conductive sheet.