To provide a trim for a roof valley part which is cut out according to the valley part of a roof, which can surely support roof tiles even if the roof tiles have a small triangular shape, prevents rain water from overflowing to both sides even if a large quantity of rain falls, and prevents sealers from being exposed to the water flowing through the valley part, and therefore enabling durability to be maintained for a long period.

This trim 1 for the roof valley part comprises: a valley covering part 11 of V-shape in plan view which is stretched on a sheathing roof board 17 along the roof valley part; vertical pieces 12, 12 vertically installed from both sides of the valley covering part 11; and tile supporting pieces 13, 13 extending from the vertical pieces 12, 12 inward at intervals from the valley covering part 11. Elastic sealers 15, 15 are installed on the tile supporting pieces 13, 13, respectively.