An air conditioning apparatus (10, 11, 12) connected to a power wire, a communication wire and a shared wire for power and communication that are included in a triplex cable, the air conditioning apparatus (10, 11, 12) comprising: a first modulator configured to modulate a first voltage signal corresponding to inputted transmission data and to output the signal as a second voltage signal between the communication wire and the shared wire for power and communication; a first demodulator configured to demodulate a third voltage signal based on the potential difference between the communication wire and the shared wire for power and communication and to output the signal as a demodulated signal; and characterized by comprising: a connector that comprises a first high-voltage capacitor (40, 41) and is configured to connect the communication wire and the shared wire for power and communication to the first modulator and the demodulator via the first high-voltage capacitor (40, 41) that withstands voltages up to a predetermined level; and a first controller configured to receive, as incoming data, serial data corresponding to the demodulated signal if the serial data includes an address of the air conditioning apparatus, to monitor the demodulated signal, and to output the transmission data that includes a destination address to the first modulator if the first controller determines that no signal is being transmitted through the communication wire. a first modulator configured to modulate a first voltage signal corresponding to inputted transmission data and to output the signal as a second voltage signal between the communication wire and the shared wire for power and communication; a first demodulator configured to demodulate a third voltage signal based on the potential difference between the communication wire and the shared wire for power and communication and to output the signal as a demodulated signal; and characterized by comprising: a connector that comprises a first high-voltage capacitor (40, 41) and is configured to connect the communication wire and the shared wire for power and communication to the first modulator and the demodulator via the first high-voltage capacitor (40, 41) that withstands voltages up to a predetermined level; and a first controller configured to receive, as incoming data, serial data corresponding to the demodulated signal if the serial data includes an address of the air conditioning apparatus, to monitor the demodulated signal, and to output the transmission data that includes a destination address to the first modulator if the first controller determines that no signal is being transmitted through the communication wire. a connector that comprises a first high-voltage capacitor (40, 41) and is configured to connect the communication wire and the shared wire for power and communication to the first modulator and the demodulator via the first high-voltage capacitor (40, 41) that withstands voltages up to a predetermined level; and a first controller configured to receive, as incoming data, serial data corresponding to the demodulated signal if the serial data includes an address of the air conditioning apparatus, to monitor the demodulated signal, and to output the transmission data that includes a destination address to the first modulator if the first controller determines that no signal is being transmitted through the communication wire.