A method for controlling luminance of an edge type backlight unit having a plurality of lamps at opposite sides of a light-guiding plate is provided that includes: analyzing luminance data for each frame of an image before outputting the image; selecting a backlight luminance level from a Look-Up Table LUT that classifies the luminance according to the analyzed luminance data; outputting lamp on/off control signals according to the selected luminance level; and providing lamp on/off signals to respective lamps according to the lamp on/off control signals.