PURPOSE: To prevent the instrusion of the sea water into a clamped portion by a method in which a covering material is surrounded on the outside projected end portion of a clamper by which the coupling part of a cabin-constituting material is clamped with a base material erected on a ship deck and also a water-tight filler is filled into between the covering material and the clamper.

CONSTITUTION: A cabin-constituting material 1 of aluminum, etc., is connected with a base material 2 of steel, etc., through a clamper 3 for a ship B'. The coupling of said clamper 3 and the base material 2 is made by means of a clamping tool 7, the projected portion of the clamping tool 7 is covered with a covering material 9, and a water-tight filler 8 is filled into between the covering material 9 and the clamping tool 7.