When a user executes an operation of requesting a client terminal for starting processing, a server starts information processing of specified contents, transmitting initial output data such as an initial screen and a sound to the client terminal. The client terminal outputs the initial data and, every time the user executes an indication input such as a command input, transmits the input information concerned to the server. The server executes information processing corresponding to the input information and generates output data common to destination client terminals as basic output data and output data for each client terminal as individual output data. The client terminal decodes an image and sound data that are basic output data and synthesizes figures and sounds based on individual output data, thereby outputting the synthesized figures and sounds.