A strain no. 153 isolated from soil degraded poly-γ-glutamate (PGA), which was produced by Bacillus subtilis (natto) . The strain formed a spore and was a Gram-positive rod, showing that this strain belonged to the genus Bacillus. We purified the PGA lytic enzyme from the culture filtrate of the bacterium by a combination of procedures, such as precipitations with ammonium sulfate (70% saturation), and chromatography on CM-cellulose, DEAE-cellulose and gel filtration. The yield of the lytic enzyme from the culture filtrate was 0.062%. The molecular weight of this enzyme was considered to be around 28, 000, which was estimated by SDS-PAGE. The optimum temperature and pH for the lytic enzyme were 60°C and pH 8.0, respectively. The enzyme was strongly inhibited by heavy metal ions, such as Hg²⁺ and Cr³⁺ and by EDTA, and may be an endopeptidase from the result of the HPLC analysis of the degradation products and its substrate specificity. The PGA lytic enzyme acted on not only substrates with a γ-peptide bond but also those with an a-peptide bond, which might be due to the contamination of other peptidase.