Abstract: This invention provides a reinforcing construction for a wall opening in a steel house capable of suppressing shearing stress to a low level while keeping, especially, the initial rigidity at a high level. Each side face wall 73 is so arranged as to be clamped between a vertical wall panel 71 and a wainscot panel 72. An opening upper frame member 57 to which a lower end of the vertical panel 71 is fixed and an opening lower frame member 54 to which an upper end of the wainscot panel 72 is fixed are fixed through metal joint 81 to each transverse frame member constituting a side face wall frame member 64 to which the side face wall 73 is fixed.