Geophysical exploration is rapidly improving with advancements in computer technology. We can now interpret the outline of a geological structure from the cross sections obtained by geophysical exploration. However, it is still difficult to objectively evaluate hydro-geological and dynamic strength structure from on site cross sections alone. In order to derive hydraulic conductivity from the electrical resistivity of layers, it is necessary to consider the tortuosity of the pore space and eliminate the effects of surface conductivity caused by charged fine particles. We have reviewed empirical equations relating electrical resistivity to hydraulic conductivity based on two idealized electrical conduction models; one for porous media and the other for fractured rock mass. We proposed techniques to calculate hydraulic conductivity from several geophysical logging data; electrical, natural gamma, and neutron logging. This method has been applied to a well where soft sedimentary rocks are distributed. The calculated hydraulic conductivity of fine sandstone, mudstone, and tuff were consistent with those of several core samples at the well. Secondly, the technique for fractured rock mass was tested at a site where the rock mass consisted mainly of granite. Estimated hydraulic conductivity from well logging data was consistent with several spikes of higher hydraulic conductivity detected by temperature logs. In the future, in order to estimate the cross sections of hydraulic conductivity and dynamic strength based on data obtained from resistivity and seismic velocity profiles, we must first reveal the relationship between geophysical data and hydraulic conductivity by laboratory tests using core samples obtained from various layers.