Abstract: Changes in physicochemical properties of kochujang pre-mixture blended with maesil extract during aging were investigated. Wheat powder was first steamed with pressure after spraying the warm water and blended with polished wheat and salt, then stored in a fermentation tank for 2 days prior to blending with different concentrations (0, 10, 20 and 30%) of maesil extract. In general, pH appeared to decrease but titratable acidity increased during aging. Control showed a significantly higher pH but lower titratable acidity. Increased maesil extract concentration up to 40% significantly decreased the pH but increased the titratable acidity regardless of time of aging (p< 0.05). Moisture content increased significantly with maesil extract content (p< 0.05) but water activity continued to decrease with the aging time in all samples. Reducing sugar content was lower with maesil extract and continued to increase during aging in all samples. Gradual decrease in NaCl content was observed during aging. The amount of maesil extract has a negative effect on L*-value but positive effect on a*-value.