In order to conserve endangered plant species in oceanic islands of Tokyo, we conducted a study with particular reference to biogeographic distribution, precise location, architecture, and light environment of individuals of Viburnum species. According to our measurements, V. brachyandrum is distributed from Oshima Island (northern limit) to Hachijojima Island, V. japonicum from Toshima Island to Hachjojima, and V. japonicum var. boninsimense in some limited islands of Ogasawara. The habitat was in the periphery (<3m) of small streams in high altitude areas (≒300 to > 600m; with typically high atmospheric moisture), and in relatively bright environment (RPPFD >13%). However, such environment has decreased due to intensive land-use and vegetation changes after human inhabitation. Herbivory on saplings by feral goats in Chichijima Island is severe, but the historical evidence of specimens shows that the local population of V. j. boninsimense has become extinct from Hahajima Island due to alternative reasons in the past few decades. Extensive plantations of Camellia japonica and invasion of exotic bamboos in the Izu Islands are also serious, and we found out that even though they are all located in the National Parks, not only their present distribution pattern, but also their past distribution must be considered when delineating the new protected areas.