A portable terminal having display buttons for displaying images corresponding to specific functions through keys pressed by a user, and a method of inputting functions of the portable terminal using the display buttons. The portable terminal includes: a controller which receives signals corresponding to a user key pressed from the plurality of input buttons and outputs image data to be displayed on each of the plurality of input buttons using the received signals; and a plurality of buttons for inputting a key from a user and outputting a signal corresponding to the key pressed, and for receiving the image data from the controller and displaying the received image data. Accordingly, by using the display buttons for displaying variable images corresponding to specific functions as well as an essential function of inputting keys from a user when a specific function is input in the portable terminal such as a cell phone, a plurality of functions can be input with only a limited number of buttons, providing speed and convenience to the user for function input.