An illuminating unit includes a reflector including a parabolic reflecting surface and an incident portion and an exit portion intersecting with each other a light source to emit a beam onto the reflecting surface through the incident portion, a light source deviation compensator disposed between the reflector and the light source to focus an image of the light source is focused to a focal point of the reflecting surface, and a light path changer to direct at least a portion of a beam with a radiation angle less than an angle of the exit portion toward the reflecting surface.