An apparatus for providing a private chat in a group chat, comprising: a display; and a controller configured to: designate at least one group chat participant selected from group chat counterparts as a private chat participant, control the display to display identification information regarding the private chat participant in a message input window (404, 704) of a group chat window (400, 708, 900, 910), the group chat window including the message input window (404, 704) and a chat log window (402, 726, 902, 912) which displays the group chat and the private chat together, wherein the message input window is commonly used for inputting a message which will be sent to the private chat participant as well as a message which will be sent to the group chat counterparts, and wherein when the identification information regarding the private chat participant is not displayed in the message input window, the message is sent to all of the group chat counterparts, and when the identification information regarding the private chat participant is displayed in the message input window, the message is sent only to the private chat participant. a display; and a controller configured to: designate at least one group chat participant selected from group chat counterparts as a private chat participant, control the display to display identification information regarding the private chat participant in a message input window (404, 704) of a group chat window (400, 708, 900, 910), the group chat window including the message input window (404, 704) and a chat log window (402, 726, 902, 912) which displays the group chat and the private chat together, wherein the message input window is commonly used for inputting a message which will be sent to the private chat participant as well as a message which will be sent to the group chat counterparts, and wherein when the identification information regarding the private chat participant is not displayed in the message input window, the message is sent to all of the group chat counterparts, and when the identification information regarding the private chat participant is displayed in the message input window, the message is sent only to the private chat participant. designate at least one group chat participant selected from group chat counterparts as a private chat participant, control the display to display identification information regarding the private chat participant in a message input window (404, 704) of a group chat window (400, 708, 900, 910), the group chat window including the message input window (404, 704) and a chat log window (402, 726, 902, 912) which displays the group chat and the private chat together, wherein the message input window is commonly used for inputting a message which will be sent to the private chat participant as well as a message which will be sent to the group chat counterparts, and wherein when the identification information regarding the private chat participant is not displayed in the message input window, the message is sent to all of the group chat counterparts, and when the identification information regarding the private chat participant is displayed in the message input window, the message is sent only to the private chat participant.