Immune response is main security against abnormalities and infection in system organ. The regulation of immune response controlled by hormone and gene regulation. Selenium was the precursors of glutathione hormone. The glutathione hormone was main hormone with high function impact against infections such as HIV/AIDS, avian influenzas, and cancer cells. The aim of this study was to analyze the selenium levels and anti-oxidant activity in kupang mussel in sidoarjo East Java. Object in this study was two groups of kupang mussels were divided based on classification. Exploration and collection sample was conduct in Sidoarjo (Candi district). Measurement of selenium level and anti-oxidant activity was performed by atomic absorption spectroscopy. The exploration result was collect two different sample, consist white kupang mussel (Corbula sp) and red kupang mussel (Corbula sp). The selenium measurement result showed that white kupang mussel was contain 0,27 ppm of selenium, the red kupang mussel was contain 13 ppm of selenium. Fascinatingly, the anti-oxidant activity, specially in white kupang mussel, was showed increasing levels at 517 nm. The study was indicated that kupang mussel in Sidoarjo East Java, contains high selenium levels to increase immune response system with potential function to inhibit the free radical activity in body.