Extracellular protease (bassiasin I), from the culture filtrate of entomopathogenic fungus Beauveria bassiana ATCC7159, was successively purified by precipitation with ammonium sulfate followed by DEAE-Sephadex A-50, CM-cellulose and Hydroxyapatite column chromatography. A typical procedure provided 41-fold purification with 13.6% yield. The molecular weight of the purified protease (bassiasin I) was found to be approximately 32,000 by SDS-PAGE. Isoelectric-focusing analysis of the enzyme showed a pI of 9. 5. NH₂-terminal sequence of the protease showed homology with those of the fungal proteases. The enzyme has an optimal pH for activity at 10.5 and is stable over pH 5.0-11.0. The maximum activity of the enzyme was at 60-65℃, and approximately 20% activity remained at 60℃ after 120 min. The protease was inhibited by phenylmethylsulfonyl fluoride (PMSF) and diisopropyl fluorophosphate (DIFP).