The Taishaku-kyo is a gorge between a limestone plateau and a limestone outcropping. Study of thevarious flora that complete Taishaku-kyo's unique landscape, as well as their preservation, have been raised asimportant topics. This research focuses on endangered plants that inhabit Taishaku-kyo, analyzes the distributionthroughout Japan of endangered plants indegenous to Taishaku-kyo, and examines endangered plants currentlygrowing in Taishaku-kyo. From an analysis of the distribution of plants throughout Japan, we can see thatwhile 15 species such as Acer mono var. taishakuense and Agropyron yezoense var. tashiroi are distributed inonly a very limited region, 5 other species showed remarkable spacial distribution, such as Rhodotypos scandensand Lonicera vidalii. Further, survey of the Taishaku-kyo confirmed that at present 10 species, including Youngiayoshinoi and Lonicera vidalii, thrive in the valley. Based on these results we can hypothesize that the peculiaritiesof the flora in Taishaku-kyo can be attributed to the fact that many species which could not grow in otherregions still are conserved here. These results also suggest that when it comes to preserving biological diversity,Taishaku-kyo is a very important ecosystem with its many endangered plant species.