A rotating machine control device is provided with: an operating terminal for changing a parameter of the rotating machine; a clearance measuring device which measures the amount of clearance between a rotor and a casing; and a control device body. The control device body, in accordance with the amount of clearance measured by means of the clearance measuring device, determines an operating amount for the operating terminal so as to vary the rate of change in the parameter, and outputs the operating amount to the operating terminal.