A user input method and device of a mobile communication terminal that includes displaying a menu screen comprising images associated with each key function and menu function necessary for terminal control, depending on a currently set operation mode; detecting a preset indicator from a video that is photographed by camera when augmented reality input mode is set, real-time synthesizing the detected indicator with the menu screen, and displaying the synthesized screen; and in a state where a predetermined one of the images and the indicator are overlapped on the synthesized screen, upon detection of a preset user motion associated with selection from the video photographed by the camera, performing an operation based on the function associated with the image.