Field manipulations of global warming are conducted to determine response of whole terrestrial ecosystems to an environmental variable in a manner that mimics climate change. Recently, ecologists from around the world have begun filed manipulations of global warming. However, plant-insect interactions in changing climate conditions are poorly known. In mature forests, most biological activities and species diversity are concentrated in the canopy, rather than in the understory. In this study, we measured leaf traits and herbivory of canopy foliage in soil and branch warming experiments of canopy Quercus crisply trees to understand how global warming indirectly affect herbivory via changes in leaf traits. For these measurements, we used canopy crane. The branch warming did not affect herbivory of canopy foliage. In contrast, the soil warming decreased herbivory of canopy foliage and altered canopy leaf traits; nitrogen and lignin decreased but total phenolics and condensed tannin increased. The decrease in herbivory can be explained by changes in these secondary compounds in canopy foliage. These results implied that plastic response of canopy leaf traits to the soil warming may have a great potential to decrease herbivore population through bottom-up regulation in mature forests.