An audio/video reproducing system, an audio/video device therein, and an audio/video reproducing method therewith are provided that allow appreciation of a great deal of audio or video using a recording medium with a small capacity.A server writes only a part of audio data read from an audio database in a recording medium. An audio reproducing device reads the audio data from the recording medium, while establishing communication connection with the server via the Internet to request lacking audio data. When an ID code and password sent from the audio reproducing device matches up with a pre-registered ID code and password, the server permits login and transmits the lacking audio data to the audio reproducing device. The audio reproducing device synthesizes the audio data read from the recording medium and the audio data sent from the server to produce complete audio data so as to reproduce audio.