Ginsan, polysaccharide isolated from the root of Panax ginseng C.A. Meyer, has been shown to be a potent immunomodulator, producing several cytokines and stimulating lymphoid cells to proliferate. In this study, ginsan was orally inoculated into BALB/c mice up to 39 days and the activity of immune cells containing macrophages and T cells was analyzed. Moreover, the production of cytokines, e.g., tumor necrotic factor-${alpha}$ (TNF-${alpha}$), interferon-${gamma}$ (IFN-${gamma}$), GM-CSF and IL-12 was also analyzed. In results, the phagocytosis of macrophages was increased. About 13% cytotoxicity of NK cells was observed in 22 days and 29 days of administration. But, oral administration did not highly affect the proliferation of T cells. In cytokine analysis, 150 mg/kg and 300 mg/kg at 22 days and 29 days showed three times more increase in TNF-${alpha}$ than the controls. IFN-${gamma}$ showed 1.07 and 1.16 times more increase at 150 mg/kg and 300 mg/kg over 22 days, respectively more than the controls. 32 days of 150 mg/kg and 300 mg/kg induced GM-CSF of about 1.3 times more than the controls. IL-12 was not induced in samples more than the controls. Ginsan could be a potential immunostimulator. Therefore, our study suggests that it can be adapted as an immunostimulator that requires a relatively short oral administration.