A mobile terminal comprising: a touchscreen configured to display an edit region for writing a message to transmit to at least one counterpart and an attach region for displaying an attachment file attached to the message; and a controller configured to, while a multimedia file is displayed on the attach region by being set as the attachment file of the message, if the multimedia file displayed on the attach region is touched and dragged to the edit region, control the multimedia file to be displayed in a manner of being inserted in the edit region, and while the multimedia file is displayed in a manner of being inserted in the edit region, if the multimedia file displayed on the edit region is touched and dragged to the attach region, control the multimedia file to be set as the attachment file of the message, wherein, if the multimedia file is set as the attachment file, the controller is further configured to determine whether the multimedia file corresponds to a 1 st file type or a 2 nd file type, wherein, if the multimedia file is determined to correspond to the 1 st file type, the controller is configured to control a popup window to be displayed on the touchscreen, to adjust an extension of the multimedia file, wherein adjusting the extension of the multimedia file comprises reducing a file size of the multimedia file in a manner of changing the multimedia file of the 1 st file type into a multimedia of a 2 nd file type having a higher compression radio, wherein when the multimedia file is inserted in the edit region, the controller is configured to control the multimedia file to lose a status as the attachment file of the message, wherein if the multimedia file is touched and dragged to an inside of a region of the edit region having a different multimedia file dis-played thereon, the controller is configured to combine the multimedia file and the different multimedia file together into a single multimedia file. a touchscreen configured to display an edit region for writing a message to transmit to at least one counterpart and an attach region for displaying an attachment file attached to the message; and a controller configured to, while a multimedia file is displayed on the attach region by being set as the attachment file of the message, if the multimedia file displayed on the attach region is touched and dragged to the edit region, control the multimedia file to be displayed in a manner of being inserted in the edit region, and while the multimedia file is displayed in a manner of being inserted in the edit region, if the multimedia file displayed on the edit region is touched and dragged to the attach region, control the multimedia file to be set as the attachment file of the message, wherein, if the multimedia file is set as the attachment file, the controller is further configured to determine whether the multimedia file corresponds to a 1 st file type or a 2 nd file type, wherein, if the multimedia file is determined to correspond to the 1 st file type, the controller is configured to control a popup window to be displayed on the touchscreen, to adjust an extension of the multimedia file, wherein adjusting the extension of the multimedia file comprises reducing a file size of the multimedia file in a manner of changing the multimedia file of the 1 st file type into a multimedia of a 2 nd file type having a higher compression radio, wherein when the multimedia file is inserted in the edit region, the controller is configured to control the multimedia file to lose a status as the attachment file of the message, wherein if the multimedia file is touched and dragged to an inside of a region of the edit region having a different multimedia file dis-played thereon, the controller is configured to combine the multimedia file and the different multimedia file together into a single multimedia file.