1. A method for providing a User Interface (UI) service in a multimedia system including a multimedia device, a UI server, and a UI client device, the method comprising: receiving, by the multimedia device, at least one UI data for representing a widget from the UI server; displaying, by the multimedia device, the received at least one UI data on a screen of the multimedia device; receiving, by the multimedia device, a request for a new widget given based on a functionality of the terminal from the UI client device; adaptively creating, by the multimedia device, the new widget by abstracting at least one UI data object in consideration of the functionality of the terminal, from among the received at least one UI data or other UI data stored by the multimedia device; displaying a proper widget on the screen of the multimedia device; separating, by the multimedia device, an input interface from the created widget; and providing, from the multimedia device to the UI client device, the separated input interface widget.