PURPOSE: To reduce the number of connecting wires to reduce a connection space and to save the manpower of connection construction work by utilizing two signal wires and a telephone circuit for both the outdoor machine and plural indoor machines of a multi-room separated type air conditioner.

CONSTITUTION: Information A which the outdoor machine 1 desires to transmit to a second indoor machine 3 is prepared as data A by an electronic controller 4, received through a transmitter 5 by the receiver 10 of a first indoor machine 2 and is sent to the electronic controller 8. The information to be sent to the indoor machine 3 is discriminated by the controller 8, sent to a telephone circuit connection device 11 and is superimposed on a telephone circuit pull-in cable 13. A signal A enters the telephone circuit pull-in cable 18 through a branching unit 14 and the telephone circuit 12 and is read by the telephone circuit connection device 16 of the indoor machine 3. In this way, the information A from the outdoor machine 1 is delivered to the indoor machine 3. Similarly, the information can be transmitted from the indoor machine 3 to the indoor machine 1 and from the outdoor machine 2 to the indoor machine 1.