Pathogenicity, morphological character, physiological and biochemical characters of bacteria isolated from diseased konnyaku ( Amorphallus konjac ) were studied and the results showed that konnyaku's soft rot was caused by Erwinia carotovora pv. carotovora . The optimum temperature, pH, carbon source and nitrogen source for the growth of soft rot bacteria was 25~30℃,6.0~6.5, lactin and yeast extract, respectively.