A plurality of client-side electronic musical apparatuses 10 are connected to a server-side electronic musical apparatus 30 through a communications network 50. Each of the client-side electronic musical apparatuses 10, which is provided with an ID, attaches the ID to a signal representative of operation of performance operators 11 and setting operators 12, and transmits the ID-added signal to the server-side electronic musical apparatus 30. The server-side electronic musical apparatus 30 independently and concurrently executes, through the use of the ID, processes corresponding to the operational signals for the respective client-side electronic musical apparatuses 10 to generate musical tone data and display data, and transmits the generated data with the ID to the respective client-side electronic musical apparatuses 10. The thus-transmitted data is appropriately received by the client-side electronic musical apparatus 10 identified on the basis of the ID. In spite of having a simple configuration, therefore, the respective client-side electronic musical apparatuses 10 are able to independently and concurrently operate as a sophisticated and high-performance electronic musical apparatus.