INSULATION PANEL FOR ROOF SUBSTRATE

PROBLEM TO BE SOLVED: To improve fire resistance efficiency and mechanical strength without complicating a structure.SOLUTION: An insulation panel 100 for a roof substrate has an insulation material 4 filled between a first steel plate 2 and a second steel plate 3, and almost a rectangular shape in planar view. The first steel plate 2 has almost a rectangular shape in planar view and almost a box form with four sides thereof folded almost at right angle. The second steel plate 3 has almost a rectangular shape in planar view and peripheral edge sections 3a to 3d of respective sides which contact with free end sections 211a to 211d of folded sections 21a to 21d of the first steel plate 2 so as to close openings of the first steel plate 2.