This study investigated changes in quality characteristics of soy sauce (Kanjang) with Gastrodia elata (GK) in aged for 6 months, and developed new soy sauce products with improved sensory characteristics. The pH level was maintained in all samples. The salinity slowly increased, and then decreased in GK 10% after 5 months. The sugar content (Brix) increased after 2 months, except in GK 10%. Crude protein and amino nitrogen contents increased with time. The optical density showed significant differences after 5 months in GK 5%. The total polyphenol contents were highest in GK 5% aged for 5 months up to 31 mg/mL. The flavonoid contents of GK 5% were highest after 5 months up to 122 mg/mL. Finally, sensory tests of GK 10% showed higher total acceptance after 2 months. The results show that an aging period of 5 months in GK 5% greatly enhanced quality characteristics.