This survey was made to give materials to the project of reclamation of the land located at the south-western foot of Mt., Fuji or northern part of Fujinomiya City where irrigation water is strongly wanted., It was tried to explain the relation between the geological construction of this area and the groundwater., There are two big springs in Fujinomiya City., One is called Wakutama and the other Shibusawa (volume 4., 7m3 /sec respectively)., There are also springs in Shinosaka and Motomurayama., At first we studied the relation between these springs and the main route of groundwater, and then the form and origin of this route., The survey was based on the observation of the surface geology and the geophysical prospecting by methos of the electric resistivity., The groundwater of this area is flowing mainly through cracks, lave tunnels and lava domes in the Fuji lavas which flooded down along valleys on the surface of the Kofuji (old Fuji) tuff breccia., In the depression at the end of these valleys, the groundwater becomes stagnant and flows out over the lowest part of the wall-rocks, forming marked springs as those of Wakutama and Shibusawa., Thus it is possible to obtain large quantities of water from this main route of groudwater., Some amounts of water may be obtained also from the Susono sands and gravels covering the lower-part of the surface of the Fuji lave flows and the Kofuji tuff breccia.,