PURPOSE:To form the conference-use electronic device with the master unit for the chairman which generates the discrimination signal to designate one of the plural slave units and the slave units which can give speaking only when receiving the discrimination signal. CONSTITUTION:The designation signal sent from the master unit is supplied to buffer register 24 from terminals 21 and 22 via gate 23. The setting code given from setting unit 25 for designation code proper to the slave unit is compared at comparator circuit 26 with the designation code of register 24. And when the coincidence is secured, relay X0 has operation. As a result, switch terminal 29 is changed over to terminal 31. Thus the speaking of the designated slave unit is delivered through output terminal 8 and 9 via microphone 6 and amplifier 27. At the same time, speaking display circuit 18 is provided to show the speaking mode through light emitting diode 13.