Changes of Enzymatic activities and chemical components during Koji preparation of soy sauce with various ratio of soy bean and wheat were studied as first step for checking the current ratio of raw materials for improved soy sauce and determination of proper ratio of them in the respect to its quality and taste, and following results could be obtained. 1. The Protease in the dryed Koji were mainly conmposed of a part which active at the neutral (about pH 6.0) range, while parts which active at acid and alkaline side were inferior. The more amount of wheat increases as raw materials of Koji, the stronger Protease activities of acid and neural side were, while the weaker alkaline side were. 2. Activity of Enzymes were increased rapidly in earlier stage then gradually in later stage or Protease and ${eta}-Amylase$ rapidly throughout except drying of ${eta}-Amylase$ during the course of Koji preparation. The more amount of wheat as raw material increases, the stronger Protease and ${eta}-Amylase$ activity except. ${eta}-Amylase$ were. 3. Reducing sugar, amino nitrogen, total nitrogen were increased, while total sugar were decreased during the course of Koji preparation. 4. The more amount of wheat increases as raw materials, the more increase reducing sugar, total sugar were, while the total nitrogen were decreased, no noticeable differences were observed in the amino nitrogen among the dryed Kojies.