In an interface apparatus provided between a first remote control system of polling communication system and a second remote control system of contention communication system, a control section executes at least one processing of the following processings based on mapping information of addresses. A first control processing is to transmit a transmission signal for controlling a second load unit to a second node unit responsive to a transmission signal which represents reception of a first input signal and is transmitted from a first terminal unit, thereby controlling the second load unit based on the first input signal. A second control processing is to transmit a transmission signal for controlling a first load unit to the first load unit responsive to a transmission signal which represents reception of the second input signal and is transmitted from the second node unit, thereby controlling the first load unit based on the second input signal.