PURPOSE: To prevent reflection from the back side of a slit part to secure positional accuracy of a light source part and the slit part by dividing a slit pipe into sections by a slit part while providing an opening on the back side of the slit part.

CONSTITUTION: A slit part 12 is formed to go through not only the surface side but also the back side so as to divide a slit pipe into two pipes 1A and 1B. Thereby, an opening part 13 is formed also on the back side. The back side of the slit part 12 has an opening 13 so as to exclude reflection from this part. An aparent light source diameter becomes small, and roundness of black matrix holes and phosphor dots, adhesiveness of phosphor dots, sharpness of black matrix holes are improved. Even when the opening part 13 is provided on the back side of the slit part 12, positional accuracy of the light source and the slit part 12 is secured with high accuracy.