The present invention relates to a back light unit which has a wide luminous view angle and uniform brightness. According to one embodiment of the present invention, provided is a back light unit which includes a curved substrate where at least one upper protrusion part consisting of a pair of inclined planes; an LED chip which is formed in one side of the inclined plane; and a diffusion plate which is separated from the upper part of the curved substrate and has one side where a reflection pattern is formed to partly reflect light emitted from the LED chip.
