A plant control system provides an enhanced capability of compensation for disturbance that abruptly changes. A controller includes a disturbance predictor for calculating a predicted value of disturbance on the basis of a drag force of a release spring and an assisting force of a compensation spring that are predicted on the basis of a clutch stroke, an adaptive disturbance observer for calculating an estimated value of disturbance on the basis of the estimated value of disturbance, a voltage to be applied to a motor, and the clutch stroke, and a sliding mode controller, which determines the voltage to be applied to the motor by carrying out control for making the clutch stroke follow a clutch stroke target value by determining the voltage to be applied to the motor by sliding mode control on the basis of the clutch stroke, the predicted value of disturbance, and the estimated value of disturbance.