A backlight unit includes a chassis, an LED, a light guide plate, a duct member, and dissipative LED attachment portion. The chassis includes a light exit portion through which light exits. The LED is arranged close to an end portion of the chassis. The light guide plate is arranged closer to a middle area of the chassis than the LED and light from the LED is guided toward the light exit portion thereby. The duct member is arranged on the side opposite to the light exit portion side of the chassis and has an air passage therein. The dissipative LED attachment portion is provided to the duct member and includes one part facing the air passage and another part protruding to inside of the chassis and to which the LED is attached.