A mobile terminal, comprising: a touch screen; a memory configured to store a plurality of images; a wireless communication unit configured to transceive data with a counterpart terminal; and a controller configured to: output a chat window including a first list of messages transceived with the counterpart terminal along a first direction such that each of the transceived messages is displayed in a form of a word balloon in the chat window, wherein the first list of the transceived messages is scrollable in the first direction in the chat window, transmit thumbnail images corresponding to selected images to the counterpart terminal in response to an input selecting the images among the stored plurality of images, characterised in that the controller is further configured to output a second list of the transmitted thumbnail images along a second direction in a single word balloon in the chat window such that the single word balloon is displayed together with the transceived messages in the chat window, wherein the second list of the transmitted thumbnail images is scrollable in the single word balloon, wherein the second direction is perpendicular to the first direction. a touch screen; a memory configured to store a plurality of images; a wireless communication unit configured to transceive data with a counterpart terminal; and a controller configured to: output a chat window including a first list of messages transceived with the counterpart terminal along a first direction such that each of the transceived messages is displayed in a form of a word balloon in the chat window, wherein the first list of the transceived messages is scrollable in the first direction in the chat window, transmit thumbnail images corresponding to selected images to the counterpart terminal in response to an input selecting the images among the stored plurality of images, characterised in that the controller is further configured to output a second list of the transmitted thumbnail images along a second direction in a single word balloon in the chat window such that the single word balloon is displayed together with the transceived messages in the chat window, wherein the second list of the transmitted thumbnail images is scrollable in the single word balloon, wherein the second direction is perpendicular to the first direction. output a chat window including a first list of messages transceived with the counterpart terminal along a first direction such that each of the transceived messages is displayed in a form of a word balloon in the chat window, wherein the first list of the transceived messages is scrollable in the first direction in the chat window, transmit thumbnail images corresponding to selected images to the counterpart terminal in response to an input selecting the images among the stored plurality of images, characterised in that the controller is further configured to output a second list of the transmitted thumbnail images along a second direction in a single word balloon in the chat window such that the single word balloon is displayed together with the transceived messages in the chat window, wherein the second list of the transmitted thumbnail images is scrollable in the single word balloon, wherein the second direction is perpendicular to the first direction.