Abstract Reactive oxygen species (ROS) were generated in all oxygen-utilizing organisms. Peroxiredoxin II (Prx II) as one of antioxidant enzymes may play a protective role against the oxidative damage caused by ROS. In order to define the role of Prx II in organismal aging, we evaluated cellular senescence in Prx II −/− mouse embryonic fibroblast (MEF). As compared to wild type MEF, cellular senescence was accelerated in Prx II −/− MEF. Senescence-associated (SA)-β-galactosidase (Gal)-positive cell formation was about 30% higher in Prx II −/− MEF. N-Acetyl- l-cysteine (NAC) treatment attenuated SA-β-Gal-positive cell formation. Prx II −/− MEF exhibited the higher G2/M (41%) and lower S (1.6%) phase cells as compared to 24% and 7.4% in wild type MEF, respectively. A high increase in the p16 and a slight increase in the p21 and p53 levels were detected in PrxII −/− MEF cells. The cellular senescence of Prx II −/− MEF was correlated with the organismal aging of Prx II −/− mouse skin. While extracellular signal-regulated kinase (ERK) and p38 activation was detected in Prx II −/− MEF, ERK and c-Jun N-terminal kinase (JNK) activation was detected in Prx II −/− skin. These results suggest that Prx II may function as an enzymatic antioxidant to prevent cellular senescence and skin aging.