A communication apparatus comprises a reception unit that receives a reception signal from a metal cable and extracts reception data; a transmission unit that sends a transmission signal obtained by modulating transmission data with a frequency included in a first frequency band to the metal cable; an interference signal detection unit that detects a signal used in wireless communication, modulated by a frequency included in a second frequency band, and transmitted over the metal cable as an interference signal; and a signal transmission control unit that instructs the transmission unit to modulate transmission data using a frequency included in a third frequency band that does not have any frequency band overlapping the second frequency band when the interference signal is detected and a frequency band overlapping both the first frequency band and the second frequency band exists.