A liquid crystal display (LCD) device having a side backlight unit that minimizes or eliminates extraneous bright lines on the LCD panel. The side backlight unit includes a lamp reflector and lamp disposed on a light incident side surface of a light guide plate. A light reflection layer is formed on the inner surface of the lamp reflector, and a transparent protective layer is formed on the reflection layer. The transparent protective layer has a thickness less than 5 micrometers. The lamp reflector has arm portions that sandwich the light guide plate on the front and back surfaces at the lamp side of the light guide plate. A light transmission region between the arm portions of the lamp reflector and the front and back surfaces of the light guide plate has a thickness less than 5 micrometers.