A server controls client apparatuses to transmit the same information to the client apparatuses without imposing workload on each client apparatus. The server is free from any interruption of the transmission of information signal unintended by the server. The server receives information designating at least one client apparatus as a destination of the information signal through a keyboard of the server, and transmits audio contents stored in a content storage hard disk to each of the client apparatuses, designated in the received designate information, through a controller and a communication unit. At least one client apparatus concurrently plays the audio content.