PURPOSE: To improve a ship comfortable to ride in, by supporting an upper structure onto a main ship body through shock absorbers, by which shaking motion of the upper structure is detected and this detection signal can control the structure to be maintained in a horizontal position, and reducing propagation of rolling and pitching motion of the main ship body.

CONSTITUTION: An upper structure 2 containing a bridge and a cabin is provided through supporting mechanisms 3 onto a main ship body 1 generating buoyancy. The mechanism 3 is provided with air springs 3a, 3b as a shock absorber. An inclinometer 8 and an accelerometer 7 are provided to the upper structure 2, and its shacking motion is detected while the detection signal is calculated by a control arithmetic unit 9, then air valves 5a, 5b, 6a, 6b controlling the pressure of air from air pressure regulators 4a, 4b are operated, and an influence due to propagation of rolling and pitching motion from the main ship body 1 is absorbed, then the upper structure 2 is maintained to a fixed horizontal attitude thus a ship is improved comfortable to ride in at its high speed sailing time.