The present invention relates to a technique which can make a backlight used in a liquid crystal display device thin and light-weighted. The present invention provides a liquid crystal display device which includes a display panel and a backlight which is arranged behind the display panel, wherein the backlight includes a film-like light guide member, a film-like light semi-transmissive member which is adhered to a first surface of the light guide member which faces the display panel in an opposed manner, a film-like reflective member which is adhered to a back surface of the light guide member opposite to the first surface, and a spot light source which is arranged at a position of the light guide member at which light is incident on the light guide member from the first surface or the back surface, and a refractive index of the light semi-transmissive member is set smaller than a refractive index of the light guide member.