The embodiments provide an additional information insertion apparatus for a broadcasting system. The system includes a broadcasting signal transmitter configured to transmit a broadcasting signal along with a data extractor configured to extract a modulated signal by dividing the modulated signal from a modulator of the broadcasting signal transmitter. An additional data generator is configured to extract synchronization of the broadcasting signal from the extracted broadcasting signal, modulate the additional information based on the extracted synchronization, and generate a level of the modulated additional information to be a smaller level than a signal level of the modulated signal by as much as a predetermined value. A data synthesizer is provided to insert the additional data from the data generator into the modulated broadcasting signal.