To obtain bright and uniform luminance by efficiently emitting light, and to prevent a moire and a bright line from occurring.

Projecting or recessed dotted parts 9 are continuously or parallelly provided side by side with the end face part 3 of incidence on the surface part 5 or the back part 6 of a light guiding plate 2, and the value of the interval for continuously or parallelly providing them is determined by dividing the distance for continuously or parallelly providing them first starting from the end face part 3 of incidence by the square root of 1.5-1.8, and the value of the next interval in the direction toward a reflecting end face part 4 is determined by dividing one by one the last interval distance by the square root of 1.5-1.8.