An electronic device performing a method of tracking a user's gaze of an electronic device and outputting an augmented reality (AR) image is provided. The metho includes outputting a first light which is a structured light at a first time point toward the user's eyes, outputting a second light at a second time point toward the user's eyes, acquiring a first image in response to the output of the first light at the first time point, acquiring a second image in response to the output of the second light at the second time point, synthesizing the first image and the second image to create a third image, calculating first coordinate values, which are coordinate values of pupils of the user's eyes on the basis of the third image; and detecting a gaze direction on the basis of the first coordinate values.