A lamp guarding unit 26 of a backlight 20 for a liquid crystal display is detachable from a lamp holding unit 24 fixed to a light-guiding plate 22 in a direction perpendicular to a light illumination surface of the light-guiding plate 22. Therefore, in replacing a fluorescent tube 44, it is not necessary to replace the whole backlight 20 or for the user to touch the fluorescent tube 44, which is difficult to handle. Because of the perpendicular removal, only a small space is needed for the replacement. Thus, the fluorescent tube 44 can be replaced safely and easily, and only a small space is required for this replacement.