A hybrid anti-rolling system was developed and equipped on board of the oceanographic research vessel “MIRAI”. The greatest advantage of the system is that it is capable of reducing a rolling motion by fifty percent at low speed, even while drifting. This enables to carry out oceanographic observations and samplings at rough seas at high latitudes. The hybrid anti rolling system has both active and passive mass movement by a pendulum mechanism which is driven by electric motors. It was proved by sea trials that the amplitude of rolling motion of the vessel was reduced to a half by the hybrid anti-rolling system in the Sea State less than 5.