To propose a method of utilizing an existent indoor lighting line for a communication line since it is necessary to lay a dedicated communication line for introducing a nurse call system in hospitals and various nursing institutions.

A communication apparatus is invented which utilizes the lighting line by adding a lighting line communication modem to the signal transmitter and the signal receiver of a nurse call system. By utilizing the present invention, it becomes possible to utilize the nurse call system at a low cost and in a short construction period even without newly laying a nurse call communication line. Furthermore, as information that can be transmitted/received, various sensor signals or room numbers are displayed and in addition to an acoustic notification, a two-way voice speech for a fixed time is enabled.