Defatted rice bran extracts were obtained by subcritical treatment using aqueous acetone as extractant. Treatment with 40% (v/v) acetone at 230 °C for 5 min yielded an extract with the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (0.274 mmol of ascorbic acid/g of bran), total carbohydrate (0.188 g/g of bran), protein (0.512 g/g of bran), and total phenolic contents (88.2 mg of gallic acid/g of bran). The effect of treatment temperature (70-230 °C) was investigated using 40% (v/v) acetone, and the extract under 230 °C treatment showed the highest levels of all the determinations described above. The extracts obtained with various concentrations of aqueous acetone were subjected to UV absorption spectra and HPLC analysis, and the results showed changes in composition and polarity. Antioxidative activity evaluated against oxidation of bulk linoleic acid of the extract obtained with 80% (v/v) acetone was higher than that not only of the extract from subcritical water treatment but also of that obtained 40% (v/v) acetone treatment.