An illumination unit includes an LED and a tabular light guide plate having a light emitting surface for emitting light from the LED as planar light, wherein a recessed portion is formed in the opposite surface of the tight emitting surface of the light guide plate, and wherein the LED is provided in the recessed portion so that the optical axis of the LED becomes parallel to the light emitting surface of the light guide plate. Further, a plurality of LEDs are arranged along the longer direction of the recessed portion, a dimming pattern is provided at a location corresponding to each of a plurality of LED of the light emitting surface of the light guide plate, and the shape or the size of the dimming pattern is varied with a location on the light emitting surface of the light guide plate.