To utilize natural resources in Indonesia, pineapple production reached 1,837,159 in 2013. Natural antioxidants developed in line with the finding of the research that has the cariogenic side effect of synthetic antioxidants for the body. Pineapple as a natural antioxidant contains of flavonoids, vitamin A and vitamin C. The research aims to determine the antioxidant activity of the water of pineapple. The water of pineapple is used in concentration of 100%, 50%, 25% for antioxidants examination was performed with a Spectrophotometric with a wavelength of 517 nm. Each of the required concentration of 100.000 ppm of the water of pineapple and mixed with 2 ml of methanol and 1 ml DPPH. The results showed that the antioxidant activity with concentration of 100% is equal to 86.20%, the concentration of 50% is equal to 56.68% and a concentration of 25% is equal to 29.32%. Conclusion from the result of this research is the water of pineapple with concentration bigger than 50% have a good antioxidant activity.