An air-conditioner control interface device that connects an air conditioner to an external device, including: an air-conditioner-information input/output unit that transmits or receives information to or from the air conditioner; an external-device-information input/output unit that transmits or receives information to or from the external device; an interface-control-information input/output unit that acquires interface control information, in which definitions of the information transmitted or received between the external device and the air conditioner and methods of transmitting or receiving the information, are described; and an interface controller that controls the external-device-information input/output unit and the air-conditioner-information input/output unit to transmit or receive information based on the interface control information.