PURPOSE: To improve workability and dimensional accuracy, and to enhance throating proper ties and design properties by unitizing a plurality of metallic roof boards peach made of one piece.

CONSTITUTION: A roofing board P is made of a metal in which an isosceles trapezoidal section 2 is connected continuously to the lower side of a rectangular section 1. The upper side and lateral sides of the rectangular section 1 are folded to the front side, the lower side of the rectangular section 1 and the lateral sides and top side of the trapezoidal section 2 are folded to the rear side, and a clearance (t), into which the lower side end section of the rectangular section 1 is fitted, is formed between the bend pieces 2c of the top side. An even number (six) of the roofing boards P are superposed in parallel crosswise, and displaced in the vertical direction in a longitudinal zigzag manner, and the lower-side end sections of the rectangular sections of the roofing boards P on the lower sides are fitted into the clearances (t) of the trapezoidal sections 2 of the roofing boards P on the upper sides. Each roofing board P is riveted at positions where the roofing boards are covered with other roofing boards P, thus manufacturing one unit U. Other units U2, U3 are displaced horizontally to one unit U1, and the lower-side end sections of the rectangular sections 1 of each roofing board P of each unit U1, U2, U3 are fitted into the clearances (t) of the trapezoidal sections 2 and unified, thus conducting roofing in a shape that a roof surface pattern (a shape) is formed in a hexagonal pattern.