A method and an apparatus for controlling an operation of a mobile terminal are preferably includes: cancelling a touch screen off mode and checking a set mode mapped to a certain key when input of the certain key is sensed while the mobile terminal is in the touch screen off mode. A screen is then displayed for executing the set mode, and displaying and processing of a signal input through a touch screen is performed. The method and apparatus provide an advantage by reducing procedures required by conventional devices in which a user process to execute a desired mode in a mobile terminal when the mobile terminal is in a touch screen off mode. By registering a function to be executed by input of one touch button key while in a touch screen off mode according to user tastes, the present invention accelerates utilization of the mobile terminal.