A display device operation method according to an embodiment of the present invention comprises the steps of: operating in a twin mode in which a merge screen obtained by merging a first screen of the display device and a second screen of another display device connected to the display device can be used by linking a plurality of display devices including the display device; displaying a pointer on the first screen; acquiring a user input for the displayed pointer; and performing an operation corresponding to the acquired user input through one or more of the plurality of display devices.