Disclosed is a backlight unit. The backlight unit includes a bottom frame having a bottom surface and a sidewall, a plurality of light emitting diodes defining a plurality of light emitting areas, at least one module substrate provided on the bottom surface of the bottom frame to support at least one light emitting diode and including a connector to supply external power to the light emitting diode, and a integrated light guide plate to bury the light emitting diode therein and provided at the light emitting areas corresponding to one screen image. Dark lines are prevented in the light guide plate and a slim backlight unit is obtained by forming a integrated light guide plate corresponding to a screen image of the display panel in the backlight unit driven by dividing the light emitting areas.