These experiments were made to investigate the characteristics of cocoon pupas. The proximate composition and fatty acids were analyzed. In order to eliminate the unfavorable odor of cocoon pupas, alkaline treatment and extraction of fat were conducted. The results were as follows. 1) The unfavorable odor can be eliminated through the extraction of fat. Boiling with n-hexane for 1 hour was the best. 2) The cocoon pupas were contaminated with $10^8$ bacterial counts/g at the first eating state. When they were stored at room temperature for 6 days, bacterial counts did not increase inure than $10^8$, but they were putrefacted with bad odor. 3) The powder of defatted cocoon pupas prepared for food material contained around 1.3% moisture, 76.0% protein, 0.8% crude fat, and 4.8% ash. 4) It was not efficient to eliminate unfavorable odor by alkaline treatment. 5) The fatty acids of cocoon pupas are composed of 0.35% myristic acid, 20.90% palmitic acid, 0.5% palmitoleic acid, 7.11% stearic acid, 32.20% oleic acid, 5.48% linoleic acid and 30.31% linolenic acid.