An augmented reality (AR) device for detecting a user's gaze and a method thereof are provided. The AR device includes a waveguide; a light reflector including a pattern; a support configured to fix the AR device to the user's face of the AR device; a light emitter and a light receiver installed on the support; and at least one processor, wherein the at least one processor is configured to control the light emitter to emit light toward the light reflector, identify the pattern based on the light received through the light receiver, and obtain gaze information of a user of the AR device based on the identified pattern.