A lighting device includes a light source lamp, and a light-diffusing layer including a diffusing plate or a diffusing sheet, the light source lamp including a folded portion (curved portion), such as U-shaped tube, and the lighting device for display devices having any of, or a combination of: the folded portion of the light source lamp is covered with a lamp frame; an optical member provided with a light-reducing or light-shielding treatment is around the folded portion of the light source lamp; the folded portion of the light source lamp is outside an effective display region; the folded portion of the light source lamp includes a member reducing or shielding light; and a reflective member with a light-reducing treatment around the folded 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.