The antioxidant effects of chungkukjang, a popular fermented soybean paste in Korea, prepared with solar salt were investigated in vitro. DJI chungkukjang(DJIC) was prepared using 3%(w/w) solar salt or 3%(w/w) refined salt, and fermented by Bacillus subtilis DJI. All of DJIC with no salt, DJIC with 3%(w/w) solar salt, DJIC containing 3%(w/w) refined salt, and commercial chungkukjang were extracted with ethanol, hexane, and water. Antioxidative activities were measured by 1,1-diphenyl-2-picryl hydrazyl(DPPH) free-radical generation, nitrite scavenging activity, peroxide value in the presence of linoleic acid, and the Rancimat test, in comparison with the commercial antioxidant butylated hydroxytoluene(BHT). Ethanol chungkukjang extracts showed the highest antioxdative capacities, whereas DPPH free-radical generation and scavenging activities, and linoleic acid peroxide values of DJIC extracts prepared using solar salt, and salt-free DJIC, showed the greatest values. In addition, extracts of DJIC prepared using solar salt had the highest antioxidant indices. Antioxidative activities were higher in DJIC extracts than in those of commercial chungkukjang. However, the antioxidative capacities of DJIC prepared using solar salt and DJIC with no added salt were less than those of BHT. In conclusion, these results suggest that extracts of chungkukjang prepared using solar salt are useful nutritional antioxidants and that dietary supplementation with such materials would decrease oxidative stress.