<p><P>PROBLEM TO BE SOLVED: To use a personal computer to simulate and verify a control logic which is to be built in a controller for operation control of a combined cycle plant. <P>SOLUTION: The control logic to be built in the controller is mounted on a simulator person computer 10 for simulating the controller, and a plant model logic 21 is mounted on a simulator personal computer 20 for plant model. When receiving an operation command signalα, the control logic 10 sends a control command signalγfor controlling the operation of a plant to the plant model logic 21. When receiving the control command signalγ, the plant model logic 21 performs simulated operation indicating the operation state of the plant, on a program and outputs an operation state signalβindicating the operation state. Since the control logic 11 and the plant model logic 21 use Linux as OS, they can be simultaneously operated on personal computers. <P>COPYRIGHT: (C)2004,JPO</p>