The object of this study is to develop a method for estimating both the ground thermometric parameter (ρ c λ) and ground conductive heat flux (G) simultaneously by using the ground surface temperature (Ts). This method is based on the Fourier series expressions of the result of heat transfer equation. The method is tested by a field-measurement. The following results are obtained: 1) The estimated ρ c λ have a reasonable value. 2) Estimated diurnal variations of G agree very well with that observed. 3) The spatial distribution of ρ c λ is also estimated from the surface temperature distribution obtained by the thermo-graphy.