A direct type backlight unit for a liquid crystal display device is provided to increase the amount of the outgoing light by regularizing the upper side emission light distribution. A reflector(12) is mounted on the cover bottom(11). A plurality of lamps(13) is arranged on the reflector to the plane. A lower prism pattern is inserted to a lower prism unit to improve the brightness between lamps. A light diffusing plate(14) is positioned on the downstream prism unit. A diffuse sheet(15) is positioned on the diffusing plate. A prism sheet is positioned on the diffuse sheet(16). A protection sheet(17) is positioned on the prism sheet.
