To provide indoor unit communication equipment capable of easily deciding that any one of the indoor unit communication equipment and outdoor unit communication equipment is abnormal.

The indoor unit communication equipment 1 is arranged in an indoor unit of an air conditioner having the indoor unit and an outdoor unit and communicates with the outdoor unit communication equipment 2. The equipment 1 comprises a controller 10 for controlling an entirety, a relay circuit 4 to be controlled to be on or off by the controller, a transmitter circuit 5 in which a transmission is controlled by the controller, and a receiver circuit 6 for receiving a transmission signal from the outdoor unit communication equipment. The controller 10 has a circuit deciding means for deciding whether a circuit connection is normal or not by turning on the relay, a self-signal deciding means for transmitting a signal from the circuit 5 if the connection is normal, receiving the signal by the circuit 6 and thereby deciding whether the circuit connection is normal or not, and a response deciding means for deciding the presence or absence of a response from the equipment 2 side to a transmission signal via the circuit 5 if a self-signal is normal.