In an LCD (Liquid Crystal Display) module, a light-guide plate is arranged on a side opposite to a display surface of an LCD panel, and cold-cathode tubes are provided to two sides of the light-guide plate Light generated by the cold-cathode tube is uniformly radiated on the LCD panel through the light-guide plate. The cold-cathode tubes generate heat together with light A panel cover is arranged to prevent heat from dissipating to the outside. Heat is conducted to part or an entire portion of the light-guide plate by using a heat conducting plate or the like