A multiplexed data producing apparatus which multiplexes N (integer) pieces of object data in which one of video data, audio data, and digital data is multiplexed to produce one piece of multiplexed data comprises a temporal storage means for temporarily storing the N pieces of object data; a control means for controlling synchronization of time information of each object data for each temporarily stored object data; and a multiplexing means for multiplexing the processed object data to produce multiplexed data.