The biodegradability of poly(vinyl alcohol) (PVA) was analyzed with respect to its molecular weight and stereoregularity using the isolated PVA-assimilating microbial strain, Alcaligenes faecalis KK314. The biodegradability of PVA was influenced by its stereoregularity, and the isotactic moiety was preferentially biodegraded. However, there is no difference in the biodegradability based on the molecular weight of PVA being larger than the octamer.