A hybrid anti-rolling system was equipped on board of the oceanographic research vessel “MIRAI”. The greatest advantage of the system has capability of reducing rolling motion by fifty percent at low speed. The system produces both active and passive moments by pendulum mechanism driven by an electric machine. The electric machine acts as an electric brake or a generator to control mass movement rapidly against rolling motion of periods between 5 and 13 seconds. The analysis of the system operations shows that the generated power is greater than consumed power, and it was confirmed with operations at sea. The result shows a possibility of operating the system with less power consumption by using an electrical regeneration control system in the future.