A backlight for a liquid crystal display device includes a plurality of point light sources 1 arranged linearly, a light guide plate 3 having a light incident surface 3a, a reflection surface 3b and a light emitting surface 3c for emitting the light reflected by the reflection surface 3b. A light scattering pattern 31 is formed on the reflection surface 3b. A light control pattern 32 is formed on the reflection surface 3b at almost entire portions except for the light scattering pattern 31 is formed for reflecting the light introduced and for outputting from the light emitting surface 3c. A pattern less area is formed on the reflection surface 3b at a boundary portion between the light scattering pattern 31 and the light control pattern 32.