To achieve homogenization of a light-emitting face without increasing thickness of a cabinet since difference in brightnesses in the normal direction at a position directly above a lamp and between the lamps becomes smaller by forming a secondary light source between the lamps.

In a backlight device having a plurality of fluorescent lamps 1 supported on a reflecting sheet 3 and arranged parallel, a diffusion plate 4 arranged and installed above the fluorescent lamps, and a reflecting member 5 arranged and installed parallel to a tubular axis at the center position between the neighboring fluorescent lamps 1, 1 on the reflection sheet 3, the reflection member 5 has a triangular cylindrical shape having a hollow inside, and a plurality of opening parts 6, 7 periodically arranged with a prescribed pitch in the tubular axis direction are installed by shifting them by a half pitch in the respective sidewalls 14, 15 of a reflecting member 5 opposed to respective neighboring fluorescent lamps 1, 1.