Objectives : The purpose of this study is to investigate the effect of Gupoongjeseuptang (GPJST) 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 GPJST on atopic dermatifis, 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 : In vivo, clinical skin severity score were significantly lower in GPJST group than control group. IgE, IL-6, $TNF-{alpha}$, IgG1, IgM, IgG2a and IgG2b levels in serum decreased remarkably in GPJST group than control group. Also, total absolute number of $CD3^+CD69^+$, and $CCR3^+$ cells recovered as normal in PBMCs and $CD3^+$, $CD3^+CD69^+$ decreased significantly compared with control group in isolated DLN from NC/Nga mouse and total absolute number of $CD11b^+Gr-1^+$, $CCR3^+CD3^+$ in dorsal skin of NC/Nga mouse decreased by GPJST. We analyzed ear and neck-back skin after biopsy and dyeing by hematoxyline/eosin (H&E) and toluidine staining (mast cells marker) and obtained results that GPJST are very effective to histological symptoms (dermal and epidermal thickening, hyperkeratosis and inflammatory cell (CD4, $CCR3^+$) infiltration). Conclusions : This study demonstrates immunological activity of GPJST on atopic dermatitis-like model mice.