the present invention provides a novel biomass plastic . the biomass plastic of the present invention is an alternative to polyethylene terephthalate and is composed of an adhesive polymeric substance . the biomass plastic is obtained by a production method including the steps of : culturing a microorganism mixture composed of bacillus subtilis , bacillus pumilus , and bacillus thuringiensis at 30 to 50 ° c . for 12 hours to 4 days in an environment including starch and silicic acid or a silicate acceptable in microbial culture ; subsequently adding corynebacterium glutamicum thereto and culturing it at 30 to 50 ° c . for 12 hours to 4 days ; and collecting the adhesive polymeric substance from culture obtained .