The Satsunan Islands, in the middle to the north of the Ryukyu Islands, Japan, are located in an important location for biogeography, as there is a shift of marine fauna in this region from subtropical to temperate. However, few have studied about marine biodiversity of this region for many taxa, with exceptions such as fishes. In this report, the biogeographic relations between the Coral Triangle region of highest marine diversity, and the Satsunan Islands, using previous reports related to species diversity of subclass Hexacorallia are reviewed. In the near future, it is strongly needed to more clearly reveal the species diversity of order Hexacorallia within the Satsunan Islands, a region of ecological variety, based on thorough and taxonomical surveys.