Illumination unit UT is used for the illumination of an LCD panel 1 from the rear side of the LCD panel 1. Illumination unit UT includes light source 2, rear cover 6 to cover light source 2 and resin frame 7 assembled with rear cover 6. Resin frame 7 is provided with stopper 73 and rib 74 disposed to restrict the movement of stopper 73 perpendicularly to rib 74. Rear cover 6 has first and second apertures 64 and 65 provided correspondingly to receive stopper 73 and rib 74, respectively. Resin frame 7 and rear cover 6 are assembled with each other by the engagement of stopper 73 and rib 74 with first and second apertures 64 and 65, respectively.