A lighting device for display devices preferably used for constituting a backlight of a transmissive or transflective liquid crystal display device includes a light source lamp, and a light-diffusing layer constituted by a diffusing plate or a diffusing sheet, the light source lamp being a light source lamp having a folded portion(curved portion), such as U-shaped tube, and the lighting device for display devices having any of, or a combination of: a configuration in which the folded portion (curved portion) of the light source lamp is covered with a lamp frame; a configuration in which an optical member provided with a light-reducing or light-shielding treatment is used around the folded portion (curved portion) of the light source lamp; a configuration in which the folded portion (curved portion) of the light source lamp is disposed outside an effective display region; a configuration in which the folded portion (curved portion) of the light source lamp is provided with a member for reducing or shielding light; and a configuration in which a reflective member provided with a light-reducing treatment is used around the folded portion (curved portion) of the light source lamp. As a result, at least part of light generated from the curved portion of the light source lamp is reduced or shielded.