A portable terminal capable of guiding a user to invoke a function and a method thereof. In the portable terminal, a voice detector detects a keyword uttered by voice corresponding to a function; a display displays guide information for guiding a user to access the function and key information indicating at least one key available to access the function, a key interface, having a plurality of keys in hardware or software, illuminates the available key according to the key information in response to an input signal; a storage stores a manual containing the guide information and the key information; and a controller controls the display to display the guide information and the key information according to the manual upon receipt of the keyword, and controls the key interface to illuminate the at least one available key according to the key information.