To provide a natural biodegradable material having both biodegradability and mechanical strength; a biodegradable film or container produced from the natural biodegradable material; and a binder to produce the biodegradable material; and a method for producing the same.

The natural polymeric material having cellulose-like characteristics with hydroxy groups which is not found in the polymeric compounds derived from petroleum and having a polypropylene-like structure, is obtained by adding and culturing microorganisms belonging to the genus Bacillus to kaoliang starch as raw materials for cultivation and collecting a polymeric viscous substance. The natural biodegradable material having biodegradability equal to that of cellulose and high mechanical strength with characteristics of polypropylene is obtained by mixing the natural polymeric material as a binder with starch and/or shell powder. The films or the containers produced by using the natural biodegradable material has both characters of the high biodegradability and high mechanical strength.