PURPOSE: To absorb pitching and rolling of moored vessel and pitching of buoy by coupling one end of yoke having the other end coupled rotatably around a bouy rotatably to an arm journaled rollably to the hull while having a weight at one end.

CONSTITUTION: Yokes 3, 5 are coupled such that one ends are rotatable through bearings 4 around a buoy 1. The yokes 3, 5 are rotatable around axes through the bearings 6. An arm 7 is journaled 10 rollably to a moored vessel 12 where a weight 11 is provided at one end while the other end is coupled rotatably to the yoke 5. An opening for making the arm 7 and the weight 11 rollable is made through said vessel 12. When constructing a weight mechanism in the yoke 3, 5 through the arm 7, pitching, rolling of moored vessel and pitching of buoy can be absorbed effectively.