The present disclosure relates to a head mounted display (HMD) capable of providing contents to a user in a state of being worn on his or her head, and may include a display unit configured to display a virtual reality image, a sensor configured to recognize objects around the HMD device, and a controller configured to display notification information associated with a preset event when the event occurs, wherein the controller detects an obstacle based on a distance between the HMD device and the recognized object among the recognized objects, and determines a position at which the notification information is displayed based on the detected obstacle.