Objectives PRAL (Prunus armeniaca Linne Var) has been known to suppress allergic reaction. However, the cellular target and its mechanism of action were unclear. This study was designed to investigate the effect of PRAL on RBL-2H3 mast cell, which is PMA-Ionomycin-induced activated in vitro and the effect of PRAL on the MNC/Nga mice that are DNCB-induced activated in vivo. Methods In this study, IL-4, IL-13 production were examined by ELISA analysis; IL-4, IL-13, IL-31, IL-31Ra, $TNF-{\alpha}$ and GM-CSF mRNA expression were examined by Real-time PCR; manifestations of AP-1 and MAPKs transcription factors were examined by western blotting in vitro. Then skin rashes have been evaluated and verified the distribution of mast cells by H&E and toluidine blue. Also, WBC, eosinophil and neutrophil, IgE level in serum, $IFN-{\gamma}$, IL-4, IL-5 in the splenocyte culture supernatant, the absolute cell numbers of $CD4^+$, $CD8^+$, $Gr-1^+CD11b^+$, $B220^+CD23^+$, $CD3^+CD69^+$ in the Axillary Lymph Node (ALN), PBMCs and dorsal skin and IL-5, IL-13, IL-31, IL-31Ra in the dorsal skin by Real-time PCR were all evaluated from the NC/BNga mice. Results As a result of this study, the mRNA expression of IL-4, IL-13, IL-31, IL-31Ra and $TNF-{\alpha}$ and IL-4, IL-13 production, shown in ELISA analysis, were suppressed by PRAL. Results from the western blot analysis showed decrease on the expression of mast-cell-specific transcription factors, including AP-1 and p-JNK, p-ERK. Histological examination showed that infiltration levels of immune cells in the skin of the AD-induced NC/Nga mice were improved by PRAL orally adminstration. Orally- administered PRAL group also showred decreased level of IgE in the serum. This group has shown decreased the level of IL-4, IL-5, but shown elevated $IFN-{\gamma}$ level in the splenocyte culture supernatant. The same group also has shown decreased cell numbers of $CD4^+$, $CD8^+$, $CD3^+CD69^+$ in the ALN, and $CD4^+$, $Gr-1^+CD11b^+$ in the dorsal skin. PRAL oral adminstration increased cell numbers of $CD4^+$, but decreased cell numbers of $CD8^+$, $Gr-1^+CD11b^+$, $B220^+CD23^+$ in the PBMCs. Conclusions Obtained results suggest that PRAL can regulate molecular mediators and immune cells that are functionally associated with atopic dermatitis (AD) induced in the NC/Nga mice. This may play an important role in recovering AD symptoms and suppressing pruritus.