This work has been carried out for many months to check whether polyethylene bag cocoon storging method bring better reeling result against the normal cotton bag storing method. The obtained results were as followings. 1. The pupa killed cocoons could be stored on the ground in case of packing in polyethylene-bag until the secondary dry process. 2. The raw silk percentage of cocoon stored in polyethylene bag, increased 0.5％ than the cotton bag storing method, not because of its reelability, but because of the better yield of cocoon bave. 3. Musty cocoon was not shown during the polyethylene hag storage, but the cocoons were attacked by rats as usually. 4. Polyethylene bag storing method invited more insects attack than the normal method, but the attack was able to cease by enclosing two naphthalene tablets in each bag.