A head mounted display (HMD) including a display unit configured to display an augmented reality image; a communication unit configured to communicate with an external device; a gaze detection unit configured to detect a gaze of a user; and a processor configured to execute a function corresponding to the augmented reality image when the augmented reality image and the external device are aligned in a first mode. Further, the first mode is a mode in which a display position of the augmented reality image remains fixed even when a position of the external device is changed, and transmit control information for displaying an execution image of the function to the external device.