PURPOSE: To perform roofing simply and at a low cost and to improve rainproofness by forming a metal roof board in such a manner as to have rising and falling parts and a crest part and a valley part and further performing shingling with a metal roof board where the crest part is formed by a fitting recessed part and a fitting projecting part and with an engaged member having an engaged part and a projecting part.

CONSTITUTION: A metal roof board 1 is formed into a rising part 2 on the ridge side, a falling part 3 on the 88'78S side, a circular arc crest part 4 and a valley part 5. Further, a part bent from the crest part 4 in the vertical direction is formed in such a manner as to have a fitting part 8 comprising a fitting recessed piece 6 and a fitting projecting piece 7. An engaged member 11 is provided with an engaged part 14 comprising a fitting projecting part 12 and a fitting recess part 13 and with a projecting part 15 to be bilaterally symmetrical about the center of the engaged part 14. The fitting part 8 of the metal roof board 8 is engaged with the engaged part 14 of the engaged member 11 fixed on a roof backing material 22, and the metal roof board 1 is pressed from above to the engaged member 11 to perform roofing. Thus, roofing can be executed simply without skill.