An apparatus for inputting commands required for controlling a mix signal and method thereof are disclosed. The present invention includes an input unit, a control unit converting an input signal received via the input unit to a per-source menu display command, the control unit controlling a per-source menu display image to be outputted based on a source information corresponding to a mix signal in accordance with the per-source menu display command, and a display for outputting the per-source menu display. Accordingly, a volume level is adjusted per a source signal included in such a mix signal as a video signal, an audio signal, and the like or an ambience (relative position) is adjusted. And, a user is always able to confirm information on a source signal (or object signal) associated with a mix signal (or synthetic object signal).