In a previous study, our group showed that the effective microorganism substance (EM-S) produced by fermentation of medicinal plants with effective microorganisms has an antiinflammatory effect on atopic dermatitis-like lesions in NC/Nga mice. However, the possible antiinflammatory effect and skin barrier function of EM-S for inflammatory cell infiltration, Interleukin-4 (IL-4) production, C-C chemokine receptor 10 (CCR10), and filaggrin (FLG) expression were not reported. Therefore, effects of EM-S on the development of atopic dermatitislike skin lesions in NC/Nga mice were evaluated. Efficacy of EM-S was judged by measurement of scratching behavior, T-cell subset infiltration, cytokine production, and FLG expression. Topical application of EM-S significantly reduced scratching behavior in NC/Nga mice caused by house dust mite antigen (Dermatophagoides farinse extract, DfE) sensitization. IL-4 production and $CD4^+$ and $CD45^+$ cell infiltrations were significantly reduced by EM-S. CCR10 expression was also significantly inhibited by EM-S. EM-S treatment also increased the level of FLG reduced by DfE sensitization. These results demonstrate EM-S, when applied topically, may be an effective substance for management of atopic dermatitis patients.