To provide a light guide plate with low cost which can uniformly distribute the light from a light source to whole part of a luminescent surface by itself, prevent the luminescent surface distant from the light source from lowering of brightness, and irradiate mainly in the direction of normal line of luminescent surface, and to provide a surface luminescence device using a light guide plate.

In order to guide the light from a light source 2, 7 insides, through a light guide surface 6 at its side, and in order to make the light disperse at luminescent surface 12, the light guide plate 1 made of a translucent material is formed into plate shape A reflection shaping part 5, comprising a light incident surface 8 approximately parallel with the light guide plate 6, at least one reflection surface 9 with an angle of inclination reflecting the light component L1 entered with an angle bigger than critical angle β, and a light emitting surface 10 approximately parallel with the light guide surface 6, is formed on a surface opposite to the luminescent surface.