This study was performed to evaluate the effect of Sorghum bicolor L. Moench(Sorghum, su-su) extracts on mouse immune cell activation. As ex vivo experiment, different concentrations(0, 50, 500mg/kg B.W.) of Sorghum bicolor L. Moench water extracts were orally administrated into mouse every other day for four weeks. The proliferation of mouse splenocytes, the number of plaque forming cells(PFC) and the cytokine IL-1β production by activated macrophage were used as indices for immunocompetence. Splenocyte proliferation was enhanced in mouse orally administrated with 50mg/kg B.W./day concentration compared to that of control group. Especially, the highest proliferation of spleoncyte was seen in the mouse orally administrated at the concentration of 50mg/kg B.W./day. The number of plaque forming cells(PFC) to SRBC were significantly enhanced when compared with control group. Also, the mouse of Sorghum bicolor L. Moench water extracts 50mg/kg B.W./day supplementation group with LPS stimulation enhanced level of IL-1$eta$ cytokine production. This study suggest that supplementation of Sorghum bicolor L. Moench water extracts may enhance the immune function by regulating the splenocytes proliferation, increasing the number of PFC and enhancing the cytokine production by activated macrophage.