This study was done to evaluate the antioxidant effect of Crataegi Fructus (CF) extract on the oxidative stress induced by reactive oxygen species (ROS), The human skin fibroblasts (Detroit 551) were cultured with various concentrations of hydrogen peroxide $(H_2O_2)$. The cytotoxicity of $H_2O_2-induced$ oxidative stress was performed by XTT assay for the cell viability according to the dose- and time-dependent treatment. For the protective effect of CF extract on $H_2O_2-mediated$ oxidative stress, cell viability, lactate dehydroganase (LDH) activity, and ferric thiocyanate (FTC) assay for the inhibitive activity of lipid peroxidation on CF extract were carried out. In this study, $H_2O_2-mediated$ oxidative stress was decreased cell viability dose-, and time-dependent manner and increased LDH activity compared with the control in these cultures. In the protective effect, CF extract increased cell viability and decreased LDH activity on $H_2O_2-mediated$ oxidative stress, especially, CF extract has antioxidant effect by the showing the inhibitive activity of lipid peroxidation by FTC assay. From these results, It is suggested that $H_2O_2-mediated$ oxidative stress was highly toxic, and also, CF extract showed the protective effect on $H_2O_2-mediated$ oxidative stress by showing the increased cell viability, decreased LDH activity and lipid peroxidation inhibition in these cultures.