A setting system of field devices may include a first communication path, a terminal device, a relay device, and a second communication path. The terminal device may include a receiving unit that receives an input operation of information, a first setting unit that performs the first setting for each of the field devices by transmitting information necessary for the first setting from the terminal device to each of the field devices through the second communication path in response to the input operation received by the receiving unit, and a second setting unit that performs a second setting for the terminal device, the second setting being necessary with the first setting for each of the field devices in response to the input operation received by the receiving unit.