A communication apparatus, includes unit extracting a reception key feature of a temporal change in received power in each frequency band contained in a received signal, unit storing, in correspondence with one another, a system name of a system which uses the frequency band, event information indicating that a communication apparatus belonging to the system starts or stops transmission, and a transmission key feature of a temporal waveform change shape of a transmission signal from a communication apparatus belonging to the system, a transmission key feature corresponding to the event information, unit determining whether there is any transmission key feature matching the reception key feature, by comparing the reception key feature with the transmission key feature, and unit selecting, when the determination unit determines that there is a matched transmission key feature, the event information and the system name which correspond to the transmission key feature from the storage unit.