To provide a field control system allowing efficient operation of a monitoring controller without increasing cost.

The field control system includes: field controllers disposed in a plant in a distributed manner; monitoring controllers performing monitoring control of the plant by communicating with the field controllers via a control bus; and an operation terminal device receiving the operation to each monitoring controller. In the field control system, the operation terminal device is connected to the control bus, and the monitoring controller receives the operation received by the operation terminal device via the control bus, and executes operation according to the operation.