To facilitate construction by providing an installation piece to extend along an upper surface and a lower surface of a side crossbeam or a beam on the side of a back surface of a recinforcing frame furnished with a handrail wall panel on the side of a surface and fastening it on the side crossbeam or the beam.

A steel made and grillwork formed reinforcing frame 12 is compounded on a back surface of a handrail wall panel 1, and frames 12a, 12b are arranged at positions corresponding to an upper surface and a lower surface of a beam 5b on a lower part of this reinforcing frame 12. Thereafter, a lower side installation piece 13b is installed on the frame 12b of a lower end part of the reinforcing frame 12, and an upper side installation piece 13a is fixed on the frame 12a of an upper end part by a bolt. Additionally, a handrail wall is formed by sandwiching the beam 5b by the lower side installation piece 13b and the upper side installation piece 13a and fixing the installation pieces 13a, 13b on the beam 5b by a bolt, etc. Consequently, it is possible to carry out construction in a simple structure.