Excoecaria agallocha (Euphorbiaceae) a mangrove plant, latex is traditionally used to for toothache, wood as anti-epileptic and root has anti-inflammatory activity. The study was conducted to investigate quantitative components and antioxidant activity of various extract. The Total Phenolic Content (TPC), total alkaloid content and Total Flavonoid Content (TFC) were quantitatively estimated. The method were employed for the evaluation of antioxidant activity are DPPH radical scavenging assay, Reducing power assay and Phospho molybdenum assay. Potent antioxidant activities were shown by the acetonitrile extract and water extract of leaf and stem in all the assays. Acetonitrile extract of leaf showing highest DPPH scavenging activity (IC₅₀ =31.76). Acetonitrile extract of leaf showing good reducing power. The better reduction of molybdenum was shown by water extract of leaf (715.5±3.5). Highest TPC and TFC were obtained for the acetonitrile extract of leaf (240.30±0.62 and 363.49±3).