first output change device for changing an output;

second output change device for changing the output with higher responsiveness than the first output change device;

first control means for controlling the first output change device so as to output a target output;

second control means for controlling the second output change device so as to output a target output;

target output change prediction means for predicting a change in the target output that occurs during a predetermined prediction period;

variable output range prediction means for predicting a change in a variable output range that can be brought about by the first output change device during the prediction period;

output out-of-range judgment means for judging whether a deviation of the target output from the variable output range is greater than a judgment value during the prediction period; and

output difference calculation means for calculating the output difference between the target output and the output changed by the first output change device;

wherein first control means causes, when the deviation is judged to be greater than the judgment value, the first output change device to start to changing the output in accordance with the variable output range; and

wherein the second control means controls, when the deviation is judged to be greater than the judgment value, the second output change device in accordance with the output difference.