In the present paper, the author's aim is to compare the karst area of Okierabu-jima with that of Hiraodai. Okierabu-jima is located in the southern part of Amami Islands and consists of raised coral limestone which is very permeable and porous. Hiraodai lies in the northern part of Kyushu main island. It is from 360 to 681 meters above sea level and is characterized by crystalline limestone which is very compact and highly jointed.
The author surveyed Doline, Karren and Limestone caves in the two areas. We can recognize the remarkable differences in the karst topography between Okierabu-jima and Hiraodai. He thinks that these differences are due to the nature of limestone and the condition of climate. In this case, he considers that me climatic conditions which characterize each climatic zone are the temperature and precipitation besides vegetation, soil (humus), groundwater etc.