PURPOSE: To provide the light transmission plate for an edge light source type plane lamp which is formable without providing the plate with an irregular reflection layer consisting of printing patterns changed in the density of fine dots, is excellent in yield and production efficiency and has the excellent uniformity of illuminance over the entire surface even in the case of obtaining a large light emitting surface.

CONSTITUTION: This light transmission plate 1 is used to convert the light of a linear light source arranged on its flank to a surface light source and is the light transmission plate for the edge light source type plane lamp which consists of ≥2 layers of the laminates of transparent substrates 11, 13 and of which the transparent substrate 11 on its exit side dispersedly contains light transmittable irregular reflection particles 12 having the refractive index at least on the surface thereof different from the refractive index of the transparent substrate 11. As a result, the light transmission plate is obtd. by forming the laminated composed of the transparent substrate 11 dispersedly contg. the irregular reflection particles and the mere transparent substrate 13. The light transmission plate is efficiently obtd. by a production system, such as injection molding system or casting polymn. system, with which mass production is easy.