The purpose of this research is verification of the heat insulation effect by sheet planting installed in metallic roof. The heat insulation effect of a grass and a Sedum was compared. And water supply and non-supply Sedum was compared. The temperature point was set to surface of each planting, the back side of planting, and surface of metallic roof under planting. The analysis object period was from Aug. 1 to 31 in 2011. The result is as follows. The surface of metallic roof amounted to 54.3ºC at highest during the experimental period. At the time of the highest temperature, the surface of grass was 44ºC and the surface of the Sedum under water supply was 46ºC. Simultaneously, the back side of grass base was 38.9ºC and the back side of Sedum under water supply base of the base was 34.5ºC. The same temperature fall effect was accepted for Sedum under water supply and Sedum under water non-supply after rain 4 days. That is, as for sedum planting, it was accepted that everyday water supply and water supply of 4 day interval have the same temperature fall effect.