A communication apparatus includes a radio-frequency transmission-reception processing unit configured to perform radio-frequency processing to a transmitted signal and a received signal; a baseband processing unit configured to perform baseband processing; a signal detecting unit configured to detect a signal from which a signal transmitted from another communication system is detected; and an interference-to-another-communication-system avoiding unit configured to suppress an interfering signal to the other communication system in radio-frequency transmission processing by the radio-frequency transmission-reception processing unit if the signal detecting unit detects a signal.