A risk assessment model which can be evaluated risk levels of toxic chemicals for human beings living in contaminated both onsite and offsite have been developed. The case studies of the risk assessment by using this model were carried out and the exposure rates, the distribution of exposure paths and the risk level of toxic chemicals in the geo-environment were estimated. The main exposure pathways of trichloroethylene (TCE) at the onsite were inhalation air, groundwater intake and crops intake, which indicates that TCE easily volatilize into the air and migrate into the pore water from the soil. The exposure rate of the inhalation air at the offsite was not so high, because the concentration of TCE in the air at the offsite was decreased by the fresh air. However, the exposure rate of the groundwater intake at the offsite had a high risk when no degradation and no adsorption of TCE occurred in the groundwater environment. Considering the adsorption or the degradation of TCE, the risk level from the groundwater intake at the offsite was not so high. To raise the precision of the evaluation, it is very important to obtain these site-specific parameters.