To provide a rainwater guide device for a folded plate roof for accurately treating rainwater spouted out of a recessed groove of an outdoor structure with the folded plate roof.

A rain gutter 6 is held and fixed to a holding part 33 formed at a cross beam 3 of the outdoor structure A, and arranged so that the upward opening of the rain gutter 6 covers the tip position of folded plate roof materials 51, 52, while a bent fixing part 82 projected facing a back face is placed and fixed to the projecting top parts 54 of the folded plate roof materials 51, 52 to install a rainwater guide plate 8. The rainwater guide plate 8 decoratively covers the tips of the folded plate roof materials 51, 52 with its covering base part 81, and positively guides rainwater flowing down from recessed grooves 53 of the folded plate roof materials 51, 52, to the rain gutter 6 by a rainwater guide part 83 inclining toward a gutter groove 62 of the rain gutter 6.