The present invention relates to a display device, which includes: a backlight unit that is divided into a plurality of blocks, driven for each of the divided blocks, and includes at least one optical assembly; a display panel that is disposed above the backlight unit; a controller that outputs local dimming values for each block corresponding to the brightness of the blocks in the backlight unit, in accordance with an image displayed on the display panel; and a BLU driver that controls the brightness of the blocks in the backlight unit, using the local dimming values for each block; in which the optical assembly includes: a first layer; a plurality of light sources formed on the first layer and emitting light; a second layer disposed above the first layer to cover the light sources; and a reflective layer that is disposed between the first and second layers, and the BLU driver outputs a plurality of driving signals in response to the input local dimming values for each block, and the driving signals each control the brightness of two or more blocks in the blocks of the backlight units.