A diffractive light guide plate comprising: a light guide unit configured to guide lights; an input diffractive optical element configured to receive lights output from a light source and diffract the received lights to be guided on the light guide unit; and two output diffractive optical elements (130, 140) disposed in a predetermined region of the light guide unit and having different linear grating patterns from each other, wherein the two output diffractive optical elements (130, 140) are configured so that each one output diffractive optical element (130, 140) receives the lights from the input diffractive optical element and allows the received lights to be directed to the other output diffractive optical element (140, 130) by diffraction, wherein the two output diffractive optical elements (130, 140) are configured so that each one output diffractive optical element (130, 140) receives lights from the other output diffractive optical element (140, 130) and allows the received lights to be output from the light guide unit by diffraction, and wherein the two output diffractive optical elements (130, 140) having different linear grating patterns from each other are alternately arranged in at least one dimension in a central region having at least a predetermined width within the predetermined region and partitioned longitudinally from a side adjacent to the input diffractive optical element to an opposite side thereto, and characterized in that, in the predetermined region, the two output diffractive optical elements (130', 140') having different linear grating patterns from each other are alternately arranged only in the central region. a light guide unit configured to guide lights; an input diffractive optical element configured to receive lights output from a light source and diffract the received lights to be guided on the light guide unit; and two output diffractive optical elements (130, 140) disposed in a predetermined region of the light guide unit and having different linear grating patterns from each other, wherein the two output diffractive optical elements (130, 140) are configured so that each one output diffractive optical element (130, 140) receives the lights from the input diffractive optical element and allows the received lights to be directed to the other output diffractive optical element (140, 130) by diffraction, wherein the two output diffractive optical elements (130, 140) are configured so that each one output diffractive optical element (130, 140) receives lights from the other output diffractive optical element (140, 130) and allows the received lights to be output from the light guide unit by diffraction, and wherein the two output diffractive optical elements (130, 140) having different linear grating patterns from each other are alternately arranged in at least one dimension in a central region having at least a predetermined width within the predetermined region and partitioned longitudinally from a side adjacent to the input diffractive optical element to an opposite side thereto, and characterized in that, in the predetermined region, the two output diffractive optical elements (130', 140') having different linear grating patterns from each other are alternately arranged only in the central region.