PURPOSE: To suppress vibration and prevent the appearance from being deteriorated by previously applying the vibrationproof countermeasures to a post and varying the characteristic frequency of the post according to the actual vibration of a hull.

CONSTITUTION: As for a post structure for vessel which prevents the vibration of the post structure such as the radar mast and foremast of a vessel, a weight 3 is installed in the radar mast body 2 in advance so as to be vertically shiftable by a winch 6, and bolts 18 and 19 or a flat steel is installed so as to be fixed through welding, and vibration can be prevented by varying the characteristic frequency according to the actual vibration of the hull.