11. A portable device comprising: a communication unit configured to communicate at least one dialog for a group chat with a server; a display unit; an input unit; and a controller configured to: control the display unit to display a group chatting window for the group chat, if a request of a user of the portable device for the group chat is detected, detect a request for an extraction of a dialog for at least one certain conversation partner of conversation partners in the group chat, extract the dialog of the at least one certain conversation partner from one or more dialogs if the request for the extraction of the dialog is detected through the input unit, and control the display unit to display the extracted dialog on a sub-chatting window, wherein the controller extracts automatically the dialog of the at least one certain conversation partner during the group chatting, and controls the display unit to display the dialog on the sub-chatting window.
11. A portable device comprising: a communication unit configured to communicate at least one dialog for a group chat with a server; a display unit; an input unit; and a controller configured to: control the display unit to display a group chatting window for the group chat, if a request of a user of the portable device for the group chat is detected, detect a request for an extraction of a dialog for at least one certain conversation partner of conversation partners in the group chat, extract the dialog of the at least one certain conversation partner from one or more dialogs if the request for the extraction of the dialog is detected through the input unit, and control the display unit to display the extracted dialog on a sub-chatting window, wherein the controller extracts automatically the dialog of the at least one certain conversation partner during the group chatting, and controls the display unit to display the dialog on the sub-chatting window. 20. The portable device of claim 11 , wherein the controller performs the group chat for the certain conversation partner in the sub-chatting window by using the transmitted or received dialog if a dialog transmission or reception event by the certain conversation partner included in the sub-chatting window is detected.