A control system comprising: a nuclear power facility and an apparatus provided therein, a main control device, an auxiliary control device, an operating signal input/output unit, wherein the main control device is arranged to output a first safety mode operating signal for operating the apparatus to safety mode when an abnormality occurs in the nuclear power facility, and arranged to output a first normal mode operating signal for operating the apparatus to normal mode when the nuclear power facility normally operates; wherein the auxiliary control device is arranged to output a second safety mode operating signal for operating the apparatus to safety mode when an abnormality occurs in the nuclear power facility; and wherein the operating signal input/output unit is arranged to receive the operating signals (S1, J1, S2) output from the main control device and the auxiliary control device, and arranged to output a third safety mode operating signal that operates the apparatus to safety mode, or to output a third normal mode operating signal that operates the apparatus to normal mode based on the received operating signals (S1, J1, S2), wherein the operating signal input/output unit includes an OR circuit arranged to output the third safety mode operating signal based on the presence of the input of the first safety mode operating signal, or of the presence of the input of the second safety mode operating signal, a NOT circuit connected to an output side of the OR circuit and arranged to output a negated third safety mode operating signal, and an AND circuit arranged to output the third normal mode operating signal based on the presence of an input of the negated third safety mode operating signal and of the first normal mode operating signal. a nuclear power facility and an apparatus provided therein, a main control device, an auxiliary control device, an operating signal input/output unit, wherein the main control device is arranged to output a first safety mode operating signal for operating the apparatus to safety mode when an abnormality occurs in the nuclear power facility, and arranged to output a first normal mode operating signal for operating the apparatus to normal mode when the nuclear power facility normally operates; wherein the auxiliary control device is arranged to output a second safety mode operating signal for operating the apparatus to safety mode when an abnormality occurs in the nuclear power facility; and wherein the operating signal input/output unit is arranged to receive the operating signals (S1, J1, S2) output from the main control device and the auxiliary control device, and arranged to output a third safety mode operating signal that operates the apparatus to safety mode, or to output a third normal mode operating signal that operates the apparatus to normal mode based on the received operating signals (S1, J1, S2), an OR circuit arranged to output the third safety mode operating signal based on the presence of the input of the first safety mode operating signal, or of the presence of the input of the second safety mode operating signal, a NOT circuit connected to an output side of the OR circuit and arranged to output a negated third safety mode operating signal, and an AND circuit arranged to output the third normal mode operating signal based on the presence of an input of the negated third safety mode operating signal and of the first normal mode operating signal.