A method of detecting the existence of an OFDM signal constituted by a plurality of carriers transmitted from another communication apparatus, includes a first selection step of selecting first carriers, where a phase difference between same carriers between symbols adjacent on a time domain is smaller than a predetermined value, from a plurality of carriers of a received signal, a second selection step of selecting second carriers, each of which has a phase of a predetermined relation of the OFDM signal with respect to another carrier, from the selected first carriers, and a carrier "determination step of determining whether the received signal has the symbols of the OFDM signal transmitted from the another communication apparatus on the basis of the selection results of the first and second carriers.