Monitoring and control system and monitoring and control method

A monitoring and control system includes a monitoring and control apparatus that transmits an instruction signal for instructing to control a target device to transmission destinations on a first and a second network by a transmission method that designates a plurality of transmission destinations and does not require responses from the transmission destinations, a controller that controls the target device according to the instruction signal and transmits process data indicating a process of the control to transmission destinations on the first and second networks by the transmission method, a transmitter that transmits the instruction signal and the process data to transmission destinations on the second network, a receiver that receives and transfers the instruction signal and the process data addressed to the transmission destinations on the second network and transmitted from the transmitter, and a monitor that receives the instruction signal and the process data.