Earth equipments are essential to protect human or other equipment from abnormal conditions. Earth resistance and potential must be restricted within low value to protect human and equipments. An estimation algorithm of earth parameters and equivalent resistivity is introduced to calculate reliable earth resistance in this research. The proposed algorithm is based on the relationship between apparent resistances and earth parameters. The proposed algorithm, which approximates the non-linear characteristics of earth by using Artificial Neural Network(ANN), estimates the earth parameters and equivalent resistivity. The effectiveness of proposed method is verified with case studies.