A backlight device, used in a liquid crystal display device, comprising: a substrate including first and second areas; a plurality of first light emitting diodes (LEDs) arranged in the first area at a density equal to or higher than a predetermined density; a plurality of second LEDs arranged in the second area at a density lower than the predetermined density; and a control unit configured to control current supplied to the first LEDs with respect to the temperature of the first area, and current supplied to the second LEDs with respect to the temperature of the second area so as to make the rate of change in effective value of the current supplied to the first LEDs different from the rate of change in effective value of the current supplied to the second LEDs when temperatures of the first and second areas are higher than a predetermined temperature.