Abstract: Disclosed is a building wall construction method for forming a decorative wall by installing wall panels of a predetermined thickness to a wall body. This method comprises steps of attaching fittings to a surface of the wall body in an upright direction at predetermined intervals, the fittings being long enough to arrange a plurality of the wall panels along each of the fittings when the wall panels face the wall body, and having through holes at predetermined intervals in a surface opposite to widthwise edge surfaces of the wall panels; and inserting nibs into the through holes of the fittings and holes formed in the widthwise edge surfaces of the wall panels and holding the wall panels so as to construct a decorative wall.