A multi-type air conditioning apparatus including an outdoor unit, indoor units, and a communication line, each of the outdoor unit and the indoor units including a communicator transmitting/receiving data through the communication line and a controller transmitting at least one preamble signal, including priority information to transmit the data using the communication line, through the communication line, and transmitting the data through the communication line when transmission of the at least one preamble signal has been completed. In the multi-type air conditioning apparatus, each of the outdoor unit and the indoor units selects a priority set time, transmits a preamble signal after the selected priority set time has elapsed, and delays data transmission when a preamble signal transmitted by another constituent unit is sensed during the priority set time, thus avoiding collision on the communication line and rapidly occupying the communication line.