Objectives : The purpose of this study is to investigate the effect of Jeseupwiryeongtang-gagam(JWTG) on atopic dermatitis by in vivo experiment using NC/Nga atopic dermatitis mouse, which has histological and clinical similarities to the atopic dermatitis of human. Methods : To investigate the effect of JWTG on AD, we evaluated atopic dermatitis-like skin lesions by clinical skin index and analyzed immunological parameters in peripheral blood mononuclear cells(PBMCs), splenocytes, draining lymph node(DLN) and performed skin histology in ears and dorsal skin of atopic dermatitis-like skin NC/Nga mouse in vivo. Results and Conclusions : In vivo, clinical skin severity score were significantly lower in JWTG group than control group. IgE, IL-6, $TNF-{alpha}$, IgM, IgG2a and IgG2b levels in serum were decreased remarkably in JWTG group than control group and $IFN-{gamma}$ production, secreted in Th1 cell were increased by JWTG. After experiment ended, we analyzed immunological cells ($CD3^+$, $CD19^+$, $CD4^+$, $CD8^+$, $CD3^+$$CD69^+$, $CD4^+$$CD25^+$ and $CD49b^+$) by flow cytometry. It resulted that total absolute number of $CD3^+$, $CD19^+$, $CD4^+$ and $CD8^+$ cells were recovered as normal and $CD3^+$$CD69^+$ were decreased significantly compared with control group in isolated DLN and PBMCs from NC/Nga mouse and total absolute number of $Gr-1^+$, $CD11b^+$ and $CD3^+$ in dorsal skin of NC/Nga mouse were decreased by JWTG. We analyzed ear, DLN, and neck-back skin after biopsy and dyeing by hematoxyline/eosin(H&E) and toluidine staining (mast cells marker) and obtained results that JWTG were effective to histological symptoms (dermal and epidermal thickening, hyperkeratosis and inflammatory cell infiltration). Ear thickness was decreased significantly than the control group and the size of inflammatory lymphocytes cells(ILC) and plasma cells(PC) in DLN were also decreased.