PURPOSE: To simultaneously communicate voices and images and to enable communication mutually between slave units by providing transmission/reception units to a lot of slave units at a base unit and modulating the frequencies of voices and images over various frequency bands at the respective slave units.

CONSTITUTION: In a base unit 1, transmission/reception with a first slave unit 2 is processed by a transmission/reception unit 7, transmission/reception with a second slave unit 3 is processed by a transmission/reception unit 8, transmission/reception with a third slave unit 4 is processed by a transmission/ reception unit 9, signals demodulated by the respective transmission/reception units 7-9 are inputted to a switch control part 10, and a connecting destination is decided by an instruction from a base unit control part 11. The voices and images to be exchanged between the slave units are frequency-modulated over the various frequency bands. Thus, speaking and the exchange of image signals between slave units can be executed, and voices and images can be simultaneously communicated.