PURPOSE: To horizontally maintain an upper structure without receiving the rolling and pitching motion of a main ship body, by both supporting the upper structure through a shock absorber onto the main ship body and providing a movable wing, which can be controlled by a detection signal of shaking motion of the upper structure, to the upper structure.

CONSTITUTION: An upper structure 2 containing a bridge and a cabin is provided through a supporting mechanism 3 onto a main ship body 1 generating buoyancy. As the supporting mechanism 3, springs 10 and dashpots 11 are provided as a shock absorber preventing rocking motion of upper and lower acceleration, pitching, etc. of the main ship body 1 from propagating to the upper structure 2. Further a horizontal tail wing 4 with a flap is provided to the rear part of the upper structure 2 and operated through a control arithmetic unit 8 and a driving gear 9 on the basis of an accelerometer 6, inclinometer 7, etc. detecting shaking motion of the upper structure 2, and the structure 2 is stably maintained for its pitching motion, then a ship is improved comfortable to ride in at high speed sailing time.