This study was conducted to optimize processing of functional seasoning sauce for instant noodles (SSIN) using response surface methodology (RSM), and to compare the functional properties of commercial SSIN. Central composite designs were adopted in the SSIN processing for ingredient formula optimization. Concentrations of sea tangle ($X_1$), traditional soy sauce ($X_2$), yeast extract ($X_3$) and Ecklonia cava extract (ECE) ($X_4$) were chosen as independent variables. The dependent variables were glutamic acid content ($Y_1$), score of sensory evaluation ($Y_2$), and antioxidative activity ($Y_3$). We found the optimal conditions to be $X_1$=3.91%, $X_2$=20.57%, $X_3$=3.04% and $X_4$=3.78%. The predicted values of the multiple response optimal conditions were $Y_1$=124.0 mg/100 g, $Y_2$=7.6 and $Y_3$=1.95. The antioxidative activity (PF, PF=oil induction period with sauce/oil induction period with distilled water) and ACE inhibitory activity of ECE-added SSIN were 1.98 and 29.0%, respectively, which were significantly higher than those of commercial SSIN (1.09 and 4.4%, respectively).