UV radiation on skin acutely caused oxidative damage and skin lesion, erythema. Oxidative damage formed because of the increase of reactive oxygen compound (ROS) and decreasing of endogen antioxidant activity that caused the damage on the skin. Pasak bumi is a plant that has antioxidant compound such as flavonoid and alkaloid that can reduce the forming of ROS due to acute UV radiation. This research was pure experimental research with rats (Rattus norvegicus) as its research subject. The used sample was 24 samples and divided into four treatment groups, that were selected using simple random sampling method. Pasak bum root was extracted using ethanol by maceration method. Superoxide dismutase enzyme activity and superoxide anion level were measured using Misra and Fridovich method; hydrogen peroxide level was measured using the colorimetric method, and erythema index was measured using chromameter based on L*a*b* coloring system. The data were statistically analyzed using post-hoc Tukey test and Mann-Whitney test with 95% of the reliable level; which resulted in significantly different results between groups that radiated by UV light and groups that were radiated by UV light and given the pasak bumi extract. Based on those results, it could be concluded that pasak bumi root extract could affect: superoxide anion level, superoxide dismutase enzyme activity, hydrogen peroxide level, and erythema index on skin rat radiated by UV light.