A polling system for use in an audio system in which a plurality of controllers for controlling a plurality of input/output devices of the audio system and a system controller for controlling the status of the plurality of controllers are connected via a bus line. In an initial polling operation upon power-up of the system, the system controller in order confirms the connection of the plurality of controllers to the system and stores the results of confirmation. When the absence of connection of the controllers is confirmed in the initial polling operation, the system controller further monitors the level on a transmission line provided in the bus line for transmitting a requesting signal from the plurality of controllers to the system controller, and performs the polling operation once more if the presence of the requesting signal is confirmed.