The objective of this research is to make isolation and identification of chemical compound nhexane fraction from methanol extract of kasturi fruit (Mangifera casturi Kosterm.) and its activity test as antioxidant and immunomodulatory. Isolation used gravity column chromatography method by adding solvent n-hexane-ethyl acetate gradient (20:1, 15:1, 10:1, 8:2, 7:3, 6:4, and 5:5)v/v. Antioxidant activity test used DPPH (2,2-diphenyl -1-picrylhydrazyl) method and immunomodulatory activity test used in-vitro. Antioxidant activity test result from isolated compounds showed a low activity, with rate IC50 12.242,7 μg/mL compared to quersetin control with rate IC50 2,96 μg/mL. Immunomodulatory activity test from isolated compounds showed an increased activity of macrophages to phagocytosis latex. Statistical analysis showed that the dose of 6.25, 12.50, and 25.00 μg/mL significantly affected the ratio of phagocytosis (RF) and phagocytic index (PI). Structure elucidation of the isolated compounds used spectroscopy FTIR, LCMS, 1HNMR, 13CNMR, and DEPT. The results of the identification found a class of terpenoid compounds, namely 17-(4-Ethyl-1,5-dimethyl-hexyl)-10, 13-dimethyl 2,3,4,7,8,9,10,11, 12,13,14,15,16,17–tetra decahydro-1H–cyclopenta [a] phenan thren-3-ol (β- citosterol)