We collected dew samples on fluorine resin sheets at forest declining and non-declining sites of Mt. Gokurakuji, western Japan, and measured chemicals in these samples. The concentrations of nitrite (HNO₂ and NO₂^-), formate, PO₄^3-, NO₃^-, SO₄^2- and NH₄+ in dew samples were much higher for the declining site than those collected at the non-declining site. In contrast, Ca²⁺, Fe and Al mainly originated from soil, showed small differences between these sampling sites, and deposition amounts were greater at the non-declining site than at the declining site. Based on the concentrations of nitrite, NO₃^- and H₂O₂, we estimated OH radical photoformation rates, and found that the rates were 0.25 μM h^-1 at the declining site and 0.023 μM h^-1 at the non-declining site. These values were approximately 6 to 32 times slower than the dew waters collected from the surface of the Japanese red pine needles at the same site. The results suggested that more OH radicals were formed on the surface of pine needles and that the dry deposition which accumulated on the pine needles probably significantly enhanced the OH formation.