Abstract
Hachijo and Mikura are blessed with freshwater setting also in Izu Islands, and two kinds, the water which was subject to the influence of rain water, and the water which was subject to the influence of groundwater, were able to be seen there. On the island which has not been blessed with fresh water, it was able to carry out focusing on investigation of groundwater and was able to see water with great influence from the sea, and water with great influence of groundwater.