The biodegradable characteristics of poly-β-hydroxybutyrate(PHB) film by fungi and soil burial are investigated. As the results of the American Standards for Testing and Materials(ASTM) method, the growth of Aspergillus niger was apparent on the PHB containing plate. This suggests that PHB was utilized as the sole carbon source by Aspergillus niger and ASTM method may have applications as measuring means of biodegradability of polyhydroxyalkanoic acid(PHA). PHB film was studied by monitoring the time-dependant changes in weight loss of PHB film under 30℃ and relative humidity 80 % during pot-test. As the results of pot-test, PHB film was decomposed about 87 % in 30 days by soil microorganisms. PHB film was more slowly degraded than PHB/HV film.