A method for controlling an operation of a mobile terminal. The method includes: entering a speed dial setting mode for setting a speed dial operation on the mobile terminal, displaying speed dial keys on the mobile terminal, when the speed dial setting mode is entered, selecting a specific speed dial key from the displayed speed dial keys, displaying a plurality of object groups corresponding to functions that may be performed by the mobile terminal, in response to the specific speed dial key being selected, selecting one of the plurality of object groups, selecting an object in the selected object group; and assigning the selected object to the selected specific speed dial key such that the selected object is performed when the specific speed dial key is manipulated.