An outdoor unit and an indoor unit communicate with each other. The outdoor unit includes a communication circuit that outputs a pulse signal to be transmitted to the indoor unit. The indoor unit includes a communication circuit that receives the pulse signal transmitted by the outdoor unit. An air conditioner 100 includes at least one photocoupler to transfer to the communication circuit the pulse signal output by the communication circuit. The communication circuit transmits a pulse signal with a first polarity and a pulse width corrected to be shorter by a predefined correction time than a predefined reference pulse width of the pulse signal.