A communications system for exchange of information between communications apparatuses by a multicarrier transmission mode using a plurality of subcarriers, the communication system includes a transmission data generator configured to generate frequency band information indicating which frequency band is to be used for transmission of data information between said communication apparatuses and a transmitter configured to transmit the frequency band information by using a specific frequency band which is set from among a plurality of frequency band assigned to the communications system, and to transmit data information by using at least one frequency band set from among said plurality of frequency bands; and a receiver configured to receive the frequency band information by using the specific frequency band, wherein bandwidths of said plurality of frequency bands are made a predetermined value, and also numbers of subcarriers in each of the bands are made a predetermined value.