PURPOSE: To improve a fine spectacle over the whole building by mounting a reinforcer, whose top is flat enough, on a corrugated roof made up of extending a crest part and a roof part alternately, and installing a sanding paint layer on top of this reinforcer.

CONSTITUTION: This roof is provided with a corrugated plate 1 made up of installing a crest part 11 and a root part 12 alternately at a constant pitch, and setting up each necking part 13 on both sides of the top of the crest part 11, and a reinforce 2 is mounted on this wavy plate 1. Then, a flat plate part 21 of this reinforce 2 is staddled between each of crest parts 11 of the folding plate 1, while both tips of each ramp of an outer leg part 22 and an inner leg part 23 are fitted in the necking part 13. Next, a sanding paint layer 211 is installed on top of the flat plate part 21 of the reinforce 2, thereby forming a roof surface into a flat as well as into such a plane as having minute irregularities. With this constitution, these irregularities serve as a nonslip role, thus operation can be facilitated.