A digital device, comprising: a front side display unit; a back side display unit installed in the opposite side of the front side display unit; a sensor unit configured to sense a user input and configured to deliver a signal according to a sensed result to a processor; and the processor configured to control the front side display unit, the back side display unit, and the sensor unit, wherein the processor is further configured to: display a front side image of at least one icon in the front side display unit, detect a first input signal for the front side image of the at least one icon, rotate the icon on which the first input signal is detected, convert the front side image of the icon to a first back side image of the icon, wherein the first back side image of the icon is displayed in the front side display unit if an application corresponding to the icon is executable in the back side display unit, detect a second input signal for the first back side image of the icon, execute the application corresponding to the icon in the back side display unit according to the second input signal, and convert the first back side image of the icon to a second back side image of the icon, wherein the second back side image of the icon is displayed in the front side display unit only if the application corresponding to the icon is currently executed in the back side display unit, wherein if a predetermined input signal for the second back side image of the icon is detected, the processor is configured to switch first image data displayed in the front side display unit with second image data displayed in the back side display unit. a front side display unit; a back side display unit installed in the opposite side of the front side display unit; a sensor unit configured to sense a user input and configured to deliver a signal according to a sensed result to a processor; and the processor configured to control the front side display unit, the back side display unit, and the sensor unit, wherein the processor is further configured to: display a front side image of at least one icon in the front side display unit, detect a first input signal for the front side image of the at least one icon, rotate the icon on which the first input signal is detected, convert the front side image of the icon to a first back side image of the icon, wherein the first back side image of the icon is displayed in the front side display unit if an application corresponding to the icon is executable in the back side display unit, detect a second input signal for the first back side image of the icon, execute the application corresponding to the icon in the back side display unit according to the second input signal, and convert the first back side image of the icon to a second back side image of the icon, wherein the second back side image of the icon is displayed in the front side display unit only if the application corresponding to the icon is currently executed in the back side display unit, wherein if a predetermined input signal for the second back side image of the icon is detected, the processor is configured to switch first image data displayed in the front side display unit with second image data displayed in the back side display unit. display a front side image of at least one icon in the front side display unit, detect a first input signal for the front side image of the at least one icon, rotate the icon on which the first input signal is detected, convert the front side image of the icon to a first back side image of the icon, wherein the first back side image of the icon is displayed in the front side display unit if an application corresponding to the icon is executable in the back side display unit, detect a second input signal for the first back side image of the icon, execute the application corresponding to the icon in the back side display unit according to the second input signal, and convert the first back side image of the icon to a second back side image of the icon, wherein the second back side image of the icon is displayed in the front side display unit only if the application corresponding to the icon is currently executed in the back side display unit, wherein if a predetermined input signal for the second back side image of the icon is detected, the processor is configured to switch first image data displayed in the front side display unit with second image data displayed in the back side display unit.