A Controller 20 sends to a Consumer 40 a command for reserving a plug/port in order to send/receive data using an Asynchronous transmission (Step 211) and receives information on a port connecting from the Consumer 40 (Step 212). The Controller 20 further sends to a Producer 30 a command for reserving a port/plug for sending content or the like (Step 213) and receives from the Producer 30 information on a Producer plug/port used for transmission (Step 214). After this, the Controller 20 notifies the Consumer 40 of the information on the port of the Producer 30 (Step 215) and receives a response from the Consumer 40 (Step 216). Next, the Consumer 40 issues a device authentication request command to the Producer 30 (Step 219) and they perform mutual device authentication and exchange of keys (Step 217).