An illumination device for a liquid crystal display (LCD) is provided, including: a flat light guide plate having a light exit surface; at least one linear source unit integrally formed with a side of the flat light guide plate and extending along the at least one side of the flat light guide plate; one or more point light sources emitting light through at least one of the side surfaces of the linear light source unit; and a plurality of light exit holes vertically passing through the flat light guide plate and arranged in a longitudinal direction of the linear light source unit between the light exit surface of the flat light guide plate and the linear light source unit, wherein each of the light exit holes has a reflective surface that totally reflects light incident on the linear light source unit into the flat light guide plate.