Background: Caulerpa lentillifera is edible macroalgae which has several biological properties. This marine plant also contains beneficial secondary metabolites that can be used for treatment and prevent several deficiencies. Objectives: This research was conducted to evaluate immunomodulatory effect on nitric oxide production and phagocytosis of RAW 264.7 murine macrophage cells from edible green seaweed of C. lentillifera extract. Methods: Extraction was applied to obtained ethanol extract, water extract and insoluble fraction. Alamar blue inclusion method was used to determine cytotoxicity and proliferation of RAW 264.7 after treated with sample. Griess assay using colourimetric commercial kits was selected to evaluate NO production and phagocytosis effect of samples was determined using phagocytic kit. Results: C. lentillifera extracts did not show any cytotoxic effect against RAW 264.7 macrophage. One hundred μg/mL of water extract increased the production of nitrite oxide. This extract revealed suspected-giant cells formation as a results of phagocytosis activity. The extract of C. lentillifera also enhanced phagocytosis activity of murine macrophage against E. coli. C. lentillifera extract enhanced activity of RAW 264.7 murine macrophage by increasing NO production and phagocytosis activity. This extract also caused suspected-giants’ cells as indicator of phagocytosis effect. Conclusion: This result provides an insight that the potency of C. lentillifera extract as immunostimulant.