A plant monitoring control device, connected via a network to a process control device that is configured to implement control of a plant based on control information, that is configured to carry out monitoring control by acquiring plant data, which are various kinds of parameter indicating a state of the plant, from the process control device, the plant monitoring control device comprising: - an input unit into which a control command for the process control device is input; - a simulator that is configured to execute a control program that simulates an operation of the process control device and is configured to carry out an operation predicting plant data after a control based on the control command is implemented; - a plant model, having a database in which are accumulated plant data acquired from the process control device, that is configured to supply plant data necessary when executing the control program to the simulator; - a determination unit including a determination logic storage unit configured to store determination logic set with respect to process details of each control of the plant; wherein the determination unit is configured to acquire predicted plant data that are a result of a predictive operation by the simulator, and the determination unit comprises a determination circuit configured to determine, based on the predicted plant data acquired from the simulator and the determination logic set stored in the determination logic storage unit, whether or not to implement a control based on the control command; and - a control unit that is configured to notify the simulator of control information in the control command and to request the predictive operation, and is configured to notify the process control device of the control information in the control command when the determination unit determines to implement a control based on the control command, wherein the control unit is configured to have a predictive operation necessity determination table, and is configured to determine using the predictive operation necessity determination table whether or not a control command input into the input unit is a control command for which a predictive operation by the simulator is necessary, to notify the simulator of control information in the control command and to request a predictive operation when determining that a predictive operation is necessary, and to notify the process control device of the control information in the control command when determining that no predictive operation is necessary. - an input unit into which a control command for the process control device is input; - a simulator that is configured to execute a control program that simulates an operation of the process control device and is configured to carry out an operation predicting plant data after a control based on the control command is implemented; - a plant model, having a database in which are accumulated plant data acquired from the process control device, that is configured to supply plant data necessary when executing the control program to the simulator; - a determination unit including a determination logic storage unit configured to store determination logic set with respect to process details of each control of the plant; wherein the determination unit is configured to acquire predicted plant data that are a result of a predictive operation by the simulator, and the determination unit comprises a determination circuit configured to determine, based on the predicted plant data acquired from the simulator and the determination logic set stored in the determination logic storage unit, whether or not to implement a control based on the control command; and - a control unit that is configured to notify the simulator of control information in the control command and to request the predictive operation, and is configured to notify the process control device of the control information in the control command when the determination unit determines to implement a control based on the control command, wherein the control unit is configured to have a predictive operation necessity determination table, and is configured to determine using the predictive operation necessity determination table whether or not a control command input into the input unit is a control command for which a predictive operation by the simulator is necessary, to notify the simulator of control information in the control command and to request a predictive operation when determining that a predictive operation is necessary, and to notify the process control device of the control information in the control command when determining that no predictive operation is necessary.