Provided is a liquid crystal display device and a backlight unit that are of high quality and have a simple configuration that a mechanism cooling a cooling medium is not included. Included are a liquid crystal display panel and an LED backlight unit including an LED light source emitting light toward the panel, and a chassis plate on which the light source is disposed, the plate including a through flow path for cooling air dissipating heat from the light source, wherein the path includes a main duct introducing the cooling air and disposed along one side of the panel, and a branch duct branching off from the main duct, aligned along a disposed direction of the light source, and including an exhaust port disposed at an end of the branch duct and discharging the cooling air to outside of the device.