The studies were carried out to screen the optimum conditions for enzymatic degumming of raw silk yarn and silk fabric by use of Alkalase, a protease produced by Bacteria, comparing with Papain and Trypsin representing natural proteolytic enzymes. 1. The optimum temperature and acidity of degumming solution were 70$^{circ}C$, pH 5-6 for Papain degumming, 40$^{circ}C$, pH 8 for Trypsin and 50-60$^{circ}C$ pH 8-9 for Alkalase. 2. By increasing the Alkalase concentration in the range of 0.6 to 1.0 gram per liter, the time for enzymatic degumming of silk yarn could be reduced by 40 minutes. 3. In degumming of silk yarn by Alkalase, the pretreatment of 95$^{circ}C$, 10 minutes at 0.1% sodium bicarbonate solution or posttreatent of 80$^{circ}C$, 20 minutes at 2% (o.w.f.) sodium silicate solution improved the efficiency of enzymatic degumming, as compared to that of nontreatment. 4. The breaking strength, elongation and Lousiness results of enzymatically degummed silk yarn were apt to be improved more than those of soap-degummed one. 5. When the pretreatment of alkaline solution was done with over 20% of degumming ratio, the enzymatic degumming efficiency of both Havutae and Crepe de chine could be reached to the same level with those of soap-soda degummed. 6. As the pretreated silk fabric with 20% of degumming ratio was under action of three proteases, respectively, the deumming efficiency of Havutae and Crepe de chine were completed by Alkalase more than by Papain or Trpysin. 7. The stiffness of enzymatically degummed Crepe de chine was not only reduced by 17% more than that of soap-soda degummed one but also the Drape coefficient was decreased in enzymatically degummed fabrics, which was closely related with the soft touch of degummed fabrics.