Abstract: The present invention relates to a head mounted display (HMD), a digital device, and a control method thereof for providing a display environment to be shared by a plurality of users. To this end, the present invention provides a head mounted display including: a processor for controlling the operation of the IIMD; a communication unit for transmitting/receiving data according to a command of the processor; and an optical shutter part for adjusting a light transmission according to a command of the processor, characterized in that the processor connects to the digital device to obtain the time-division display information of the digital device containing the display time information of a first display content and a second display content of the digital device which are alternately displayed, so as to open or close the optical shutter part according to the time-division display information.