PURPOSE: To standardize the hardware for a common service by fixing a cross section-L-shaped engagement member with one end of a board in the longitudinal direction and installing an adjusting screw and a fastening screw to one engagement member and the other engagement member respectively.

CONSTITUTION: In the case when fixing an upper wall W, a board 1B of a mounting metal fitting 1 is placed into contact with the rear side of the wall board W while an engagement claw 5 is engaged with the upper end of the wall board W so that they are positioned, thereby fixing the metal fitting 1 on the rear side of the wall board with a mounting bolt S. The other piece of an engagement piece 2b is engaged with a steel structural material R where an elevation error of the wall board W is corrected by means of an adjusting screw 4A. Furthermore, in the case when fixing the wall board W with the lower part of a window frame or the like, the upper part of the board 1B located at a higher elevation than the part of the engagement claw is cut and removed so as to use.