To provide biodegradable plastics and their molded products having better processability and physical properties than the conventional naturally- derived materials using konjak as a principal raw material capable of reducing cost.

The method of producing biodegradable plastics comprises the steps of plasticating konjak powder by adding water so as not to generate fluidity, kneading to form pellet shape biodegradable plastics, where a natural material additive is incorporated during kneading. The biodegradable molded articles are produced from the biodegradable plastics derived from konjak as a molding material via press or extrusion molding into desired shape.