Biodegradable plastic is used for TANAKA's original paper bags' handles. Biodegradable plastic which keeps good performance as various plastic products, is decomposed by natural microorganisms after being disposed, and ends up as water and CO2 to be decomposed by plant, having an earth-friendly process of going back to nature. It is now widely used in various industrial circles such as automobile industry, computer industry, consumer-electronics industry and so on. Biodegradable plastic could be classified into three groups by material composition, which are 1. microorganism family, 2. natural polymer family and 3. synthetic polymer family. Apart from full biodegradable plastic, non-environment-friendly plastic which is modified from general-purpose plastic by adding biodegradable additive agent, and photochemical degradable plastic which is decomposed by ultraviolet irradiation in a natural environment are generally distinguished from biodegradable plastic since they are not totally degradable.