An air conditioner includes at least one indoor unit and a wired controller connected to the indoor unit through two lines to receive power from the indoor unit and to perform data communication with the indoor unit. Each of the indoor unit and the wired controller includes a communication unit that modulates a low-frequency communication signal into a high-frequency communication signal and transmits the high-frequency signal and demodulates a received high-frequency signal into a low-frequency signal. When a plurality of indoor units and a wired controller perform communication, a communication signal is transmitted after being modulated into a high-frequency signal and linking the high-frequency signal with DC power. This reduces the inductance of an inductor required to separate the linked high-frequency signal into DC power and a communication signal and the capacitance of a capacitor required to link the signal with DC power, reducing PCB size and inductor and capacitor costs.
