PURPOSE: To increase the bonding strength to a folded board roofing.

CONSTITUTION: An over-roofing folded board mounting device comprises a supporting member 21, a structure mounting transfer plate 22 set over between the crests of a folded board roofing, a pressure plate 23 folded in the center into an angle form and installed in the cavity bounded by these supporting member 21 and transfer plate 22, and a holddown bolt 25 to press the angle-form crest 24 of this pressure plate 23 and attach the supporting member 21 by pressure to the neck of the crest of the folded board roof. The two end foldings 23a of the supporting member 21 are attached by pressure to the neck of the crest by fastening the pressure bolt 25 to result in increase of the fitting force, which allows enhancing the certainty in fixation and the reliability remarkably, facilitates the mounting works, and reduces labors therein.