The present disclosure relates to a flat panel display with an optical image sensor embedded therein. The flat panel display includes a directional light unit. The directional light unit comprises a cover substrate with a surface area corresponding to the length and width; a first low refractive index layer attached to the lower surface of the cover substrate; a light-exiting element disposed to correspond to the display area, on the lower surface of the first low refractive index layer; a light-entering element disposed outside the display area at one side of the light-exiting element, on the lower surface of the first low refractive index layer; a second low refractive index layer disposed on the lower surfaces of the light-exiting element and light-entering element and attached to the upper surface of the display panel; and a light source disposed to face the light-entering element.