The present invention relates to a head mounted display device, an operating method for the device, and a storage medium. According to one embodiment, a head mounted display device comprises: at least one display; at least one camera arranged on the rear surface of the at least one display; a control unit; and a memory for storing a plurality of commands executable by means of the control unit, wherein executing the commands allows the control unit to perform a plurality of operations, the plurality of operations comprising: acquiring an image of both eyes of a user through the at least one camera; detecting both eyes of the user from the acquired image; measuring the binocular distance of the user on the basis of both eyes of the user, having been detected from the acquired image; converting an image on the basis of the measured binocular distance; and providing the converted image to the at least one display, and the at least one display can display the converted image.