An interior lighting display device and a display panel thereof capable of effectively preventing a dark area from being formed in the display panel are provided. A film or sheet 30 that reflects light is disposed on the back surface and the side surface of a display panel 16 of an interior lighting display device. For example, the film or sheet is disposed on a back surface and a side surface of a region 22 that is a colored area having low transmittance of the display panel, and an area in which a light source is not present behind the display panel. In addition, a light reflective body is placed in an area in which the light source is not present within the interior lighting display device.