This study examined the antioxidant activity of methanol and water extracts from Orostachys japonicus A. Berger according to harvest times, by measuring electron donating ability(EDA), reducing power, superoxide dismutase(SOD)-like activity, thiobarbituric acid reactive substances(TBARS) and antioxidant activity within a linoleic acid emulsion. EDA increased proportionally with the extract concentration and the methanol extract had slightly stronger effects than the water extract. And reducing power and SOD-like activity were highest in the methanol extract. Overall, based on the data, the methanol extract of O. japonicus A. Berger harvested during $August{sim}October$ presented the highest level of antioxidative activity and may be a good candidate as a natural antioxidant source.