PURPOSE: To raise the safety of a tower by a method in which a manhole is provided on the tip of the tower, a handle to open or close a valve through which water is charged and a ladder are provided in the tower, and the bottom of the tower is connected with a mat.

CONSTITUTION: The coupler 4 of a tower 1 for regulating settlement is connected with a coupler 14 provided to the sloped face 25 of a steel mat 21, and the tower 1 is fixed to the mat 21 by means of bolts 2. The mat 21 is settled to seabed, a manhole 5 is opened by worker, and part of the bolts 2 is removed by worker coming into the tower 1 along a ladder provided in the tower 1. A handle 6 is then turned to open the valve 8 to charge water into the tower 1, and then the remaining bolts 2 are removed by diver coming into the tower 1. The tower 1 is dagged and removed by using an eye plate 15 by means of tug boat, etc.