PURPOSE: To contrive to stabilize the attitude of a ship, by a method wherein the horizontal force component of a wind against a sail is obtained from detected values of wind velocity and wind direction, and a mast is tilted to the windward side so as to exert a reactional moment in accordance with the horizontal force component obtained.

CONSTITUTION: When a wind blows transversely to the ship 1 and collides against the sail 2, a tilting moment is exerted on the ship 1 by the horizontal force component Fy of the wind. In this case, when cylinders 6, 6 are operated to tilt the mast 3 to the windward side, the total weight Wm of the mast 3 and the sail 2 is displaced to the windward side, and the tilting of the ship 1 is corrected. Driving of the cylinders 6 is controlled by detecting the wind direction (a) and wind velocity (b) by a detector 7, calculating the horizontal force component Fy from the detected values by a calculator 8, obtaining an angle θ2 by which the mast 3 is to be inclined, comparing the angle θ2 with a signal from an inclination angle detector 9 by a comparator 10, and driving the cylinders so as to reduce the angle difference to zero.