A light emitting element is mounted on the surface of a board. The light emitting element emits light. The light passes through a translucent optical member. The light enters the translucent optical member through a incident surface. The lines of protrusions make the incident surface jagged. The jagged surface resulting from the protrusions enables diffusion of the light entering through the incident surface. The light spreads along the surface of the board. Simultaneously, the emitted light is partly reflected on the incident surface. The reflected light is reflected on a reflecting surface placed behind the light emitting element. The reflected light then enters the translucent optical member. The translucent optical member is thus allowed to illuminate over a wide range with a sufficient brightness. An impressive illumination can be realized.