Provided is a device for resizing a JPEG image having a nonstandard size at a predetermined ratio to output the resized image on a display unit without distortion in a mobile communication terminal. A method for processing a JPEG image in a mobile communication terminal comprises extracting image sizes (X, Y) from JPEG data of a JPEG file stored in an image data storing unit, comparing display area sizes (dx, dy) of the display unit with the image sizes (X, Y), and resizing the image sizes (X, Y) while maintaining the ratio of width:length in consideration of the display area sizes (dx, dy) to output the resized image to the display unit.