An analog signal input/output system in which an analog signal input terminal converts an input analog signal to a digital signal and transmits the digital signal to a host computer via a network, while a digital signal generated by the host computer is transmitted through the network to an analog signal output terminal and converted therein to an analog signal to be outputted. Two connections of upstream and downstream sockets between the host computer and the analog signal input/output device. These connections are selectively used to provide communication of control signals and data. Exemplary analog signals include input signals from a microphone, output signals to a speaker, and input/output data to/from a sensor, a measuring device and the like.