To provide a communication apparatus, a transmitting device and receiving device which can reduce a PAPR in a simple structure without executing complicated processing.

A communication system, designed to transmit signals using a multicarrier, comprises a transmitting device which includes a transmit side phase rotator which rotates, by 180°, the phase of a rule-conforming half of a plurality of first mapping signals mapped on coordinate axes to generate a plurality of second mapping signals and an IFFT circuit which modulates a plurality of subcarrier signals whose frequencies have orthogonal relations based on the plurality of second mapping signals; a receiving device which includes an FFT circuit which performs FFT processing on a received time domain signal to output the plurality of second mapping signals of a plurality of subcarrier signals and a receive side phase rotator which rotates, by 180°, the phase of half the plurality of second mapping signals conforming to the same rule as for the transmit side to generate the plurality of first mapping signals.