A method for controlling a head mounted display (HMD) includes detecting an external device, displaying an augmented reality image as a first mode, changing the first mode to a second mode when the gaze of the user to the augmented reality image is detected in the first mode, and executing a function corresponding to the augmented reality image when the augmented reality image and the external device are aligned in the second mode. The first mode is a mode in which a display position of the augmented reality image depends on a position of the external device the second mode is a mode in which the display position of the augmented reality image remains fixed even when the position of the external device is changed.