A metadata transmitter synchronized with multimedia contents comprises: a multimedia contents authoring unit for generating and editing multimedia contents; a multimedia contents format converter for compressing the multimedia contents, converting them into a transmission format, and outputting them; a metadata authoring unit for generating and editing metadata for describing the multimedia contents, the metadata including transmission types and transmission information; a metadata format converter for converting the metadata into binary codes, converting the converted metadata into a synchronization format for synchronization with the multimedia contents and a transmission format, and outputting them; and a multiplexer for multiplexing the multimedia contents format and the metadata format respectively output from the multimedia contents format converter and the metadata format converter into a stream, and outputting it.