To provide a soil contamination evaluation method to be able to select soil purifying treatment area effectively and to provide a soil purifying treatment method using the evaluation method.

The soil contamination is estimated on the results of the method to analyze soil property and contaminated materials of soil (S101, S102) at plural places, to analyze three-dimensional structure of soil and also estimate a contamination source of the contaminated materials (S210, S202), to determine a behavior of groundwater observation point (S203) based on the result and observe a behavior of groundwater in the soil (S103, S104), estimate a behavior of the contaminated materials in the soil (S204, S205) based on the results of the three-dimensional structure of the soil, the contamination source and behavior of groundwater, investigate the detailed investigation points (S206, S105-S107) to be determined based on the results of the behavior estimation, and to correct the result of the behavior estimation of the contaminated materials in the soil (S207, S208) based on the results and to evaluate the degree of soil contamination.