There is provided a backlight unit.The backlight unit is configured to include: a plurality of light sources; a plurality of light guide plates being arranged alternately with the light sources so that light emitted from the light sources is incident; and a chassis receiving the light sources and the light guide plates, wherein the plurality of light guide plates are disposed to be spaced apart from each other, being symmetrical to each other in order to face the central region of the chassis, a pair of light guide plates opposed to each other on the central region being connected to each other so that the light therefrom is mixed.