The brain during developmental period is thought to be highly sensitive to environmental insults　including exposure to pollutants. We have reported that maternal exposure of experimental animals to low doses of polutants, such as dioxin and arsenic, induced social behavioral abnormalities later in life. To understand deeply which types of social behaviors are sensitive to environmental pollutants, we designed novel behavioral test paradigm in mice, which can evaluate individual recognizing ability of mice. In the results, mice who maternally exposed to low doses of dioxin showed lowed recognizing ability than control mice.