PURPOSE: To simplify the structure and facilitate the handling by a method wherein a foamed material is inserted in a space defined by a lower frame with a rail, an upper frame, and colored iron sheets connected to a vertical frame.

CONSTITUTION: A front colored iron sheet 12 and a back colored iron sheet 13 are interconnected through a colored iron sheet 14 and a urethane foamed material 15 is inserted in a space defined by the iron sheets 12, 13, and 14. A vertical frame is disposed between a lower frame 16 with a rail supported by the iron sheets 12-14 and the foamed material 15 and an upper frame 17 with a guide to form a wall panel member. Vertical frames 22a and 22b are fixed to the left and the right of the periphery of a window glass 21 and rail frames 23a and 23b are fixed to the upper and lower parts of the periphery of the window glass 21 to form a window glass assembly 20. Further, the window glass assembly 20 is inserted in the wall panel member.