Platanthera brevicalcarata Hayata (Orchidaceae), previously known to be distributed from Tai-wan to southern Japan, was found in the Jeju-do, Korea. This species is distinguished from the related taxon Platanthera chlorantha by its small plant size, white sepal with distinct one green vein, and short-cylindrical spur. The local name Young-ju-je-bi-ran is originated from the local name of Mt. Halla. The morphological characters and illustration of the species are provided with line drawing and photograph from the natural habitat.