To provide a control method for reducing oscillation using a plurality of small fins.

Control data is made by combining continuous time series data for a preset period of time and an instantaneous response data using a plurality of actuators and a control signal for each of the actuators is independently set. The ranking of the sizes of plural oscillations, the computation of parameters representing oscillation characteristics, and the computation of parameters representing the effect of reducing the oscillations are performed in accordance with the frequency analysis results of time series data for both the movement of a hull to be measured and the estimated movement of the hull with the operation of each of the actuators under control. The control parameters required for processing are changed for every certain time.