To easily confirm the current mixing state and a route where the mixed signals are outputted via the display of a screen.

An audio mixing system main body 1 mixes the audio signals inputted via a voice input line 5 at a matrix part and outputs these mixed signals via a voice output line 6. A navigation device 4 of the main body 1 is provided with a signal processing means 7 which processes the audio signals inputted from the line 5 and outputs these signals from the line 6, a control means 8 which controls plural signal processing parts constructing the means 7 and also controls a connection with which these signal processing parts are connected to each other, an instruction means which gives the control instructions to the means 8 and a display means 3 which shows the control state of the means 8 on a screen. Then the connection state of each signal processing part is searched by pointing out the relevant signal processing part of the means 7 on the displayed screen, and the searching result is displayed on a screen of the means 3.