As in the measurement of ground resistance by using the 3 point fall-of-potential method, it is known that the distance of current electrode should be at the point of showing the plateu on the potential curve. But the problem is that it my be practically impossible to meet the condition in actual sites. For solving such a situation, this paper provides the least distance of current electrode according to the analysis for the test-field measurement showing that it is feasible to measure the ground resistance in the two in current electrode distance as the length of driven-rod type electrode and the some district length of mesh electrode.