Abstract: Provided are a method and device for setting control authority and providing additional information when content is shared. A device control method for controlling a user device having a display includes displaying content on the display of the user device by using a screen sharing service for sharing the displayed content with an external device; transmitting control authority setup information indicating that the user device has control authority of the screen sharing service, to the external device; and transmitting a control command associated with the screen sharing service to the external device according to the control authority.