This paper presents impedance characteristics of grounding electrodes on earth surface in comparison with those buried underground. The impedance characteristics are investigated analytically, experimentally and numerically. It has been found that there exists no significant difference of a transient resistance between a grounding electrode on the earth surface and a conventional buried electrode, when the electrode length is greater than some 10m. The result agrees with that evaluated by well-known Sunde's formula for a steady-state resistance of a grounding electrode.