A head mounted display device, comprising: a display unit configured to display a virtual reality image; a sensor configured to recognize objects around the head mounted display device; and a controller configured to display a notification information associated with a preset event when the event occurs, wherein the controller is further configured to: detect an obstacle based on a distance between the head mounted display device and a recognized object among the recognized objects, and characterized in that the controller is further configured to: determine whether or not the notification information is a first notification information that requires a user's interaction, wherein the user's interaction is a user's gesture, when the notification information is the first notification information, determine a position at which the first notification information is to be displayed based on the detected obstacle, and display the first notification information at the determined position to prevent the user from being injured due to the detected obstacle when the user makes the user's interaction, and when the notification information is a second notification information that does not require the user's interaction, display a region including the second notification information in a semi-transparent manner. a display unit configured to display a virtual reality image; a sensor configured to recognize objects around the head mounted display device; and a controller configured to display a notification information associated with a preset event when the event occurs, wherein the controller is further configured to: detect an obstacle based on a distance between the head mounted display device and a recognized object among the recognized objects, and characterized in that the controller is further configured to: determine whether or not the notification information is a first notification information that requires a user's interaction, wherein the user's interaction is a user's gesture, when the notification information is the first notification information, determine a position at which the first notification information is to be displayed based on the detected obstacle, and display the first notification information at the determined position to prevent the user from being injured due to the detected obstacle when the user makes the user's interaction, and detect an obstacle based on a distance between the head mounted display device and a recognized object among the recognized objects, and characterized in that the controller is further configured to: determine whether or not the notification information is a first notification information that requires a user's interaction, wherein the user's interaction is a user's gesture, when the notification information is the first notification information, determine a position at which the first notification information is to be displayed based on the detected obstacle, and display the first notification information at the determined position to prevent the user from being injured due to the detected obstacle when the user makes the user's interaction, and determine whether or not the notification information is a first notification information that requires a user's interaction, wherein the user's interaction is a user's gesture, when the notification information is the first notification information, determine a position at which the first notification information is to be displayed based on the detected obstacle, and display the first notification information at the determined position to prevent the user from being injured due to the detected obstacle when the user makes the user's interaction, and when the notification information is a second notification information that does not require the user's interaction, display a region including the second notification information in a semi-transparent manner.