Provided is an augmented reality (AR) display device. The AR display device includes an optical engine configured to output light of a virtual image and a light guide plate including a first region that receives the light of the virtual image, a third region that outputs the light of the virtual image, and a second region that propagates the light of the virtual image input to the first region toward the third region, in which a pupil expansion grating is formed in the second region to duplicate the light of the virtual image incident to the first region into a plurality of beamlets, and in the third region, an output grating array is formed in which a plurality of small diffractive grating regions are arranged at intervals equal to or less than a size of a pupil, in which a diameter of each of the plurality of small diffractive grating regions is equal to or less than the size of the pupil.