The antioxidant activity and total phenolic content of Sonneratia ovata Back, a mangrove plant, were investigated in this study. Methanol was used to extract the leaf, fruit, stem bark, and root of S. ovata Back. The antioxidant assay was conducted using the scavenging radical DPPH, and the total phenolic content was measured following the Folin Ciaocalteu method. Methanol extract from leaves of S. ovata Back presented the highest antioxidant activity than stem bark, root, and fruit. The IC 50 were 4.07 mg/L, 25.94 mg/L, 100.94 mg/L, and 195.83 mg/L, respectively. The total phenolic content of leaf (52.00 mgGAE/g) was higher than fruit (14.06 mgGAE/g). This study suggested that the methanolic leaf extract of S. ovata Back contained a potential source of natural antioxidants more than the other parts.