A backlight structure has light source modules (1, 1) disposed at its upper and lower edges, a light guide plate (2) disposed between the light source modules (1, 1), a rear plate (3) disposed at the back of the light source modules (1) and light guide plate (2), a fan mounting plate (4) disposed at the back of the rear plate (3), and a cooling fan (5) attached to the fan mounting plate (4). Projections (3a) are formed on the rear plate (3), at portions at the back of the light source modules (1, 1), and a flat surface (3b) is formed between the upper and lower projecting parts (3a). A cooling air passage (11) is formed between the front surface (4a) of the fan mounting plate and the flat surface (3b) of the rear plate. The heat of LED chips (1a) of the light source modules is concentrated on the projecting part (3a) of the rear plate and released from the cooling fan (5) to the outside by the air guided to the cooling air passage (11).