The enzyme properties of protease of the Pleurotus Cornucopiae (Pers.) Rolland were investigated by purification with gel filteration using DEAE-sephadex A-50, CM-cellulose, DEAE-cellulose and Sephadex G-75. Two kinds of active fractions were isolated from this mushroom study. The active fraction showed protease activity for the bovine serum albumin substrate, and its optimum pH, optimum temperature, pH stability and thermal stability were 4.0, 50℃, 3.0∼4.0 and 20∼40℃, respectively. The activity of the enzyme was inhibited by Ca^(++), Cu^(++), Zn^(++), Fe^(++) and Mg^(++), but increased with Co^(++). The enzyme had one subunits composed of 17 amino acids. The apparent molecular weight was about 56,000 daltons.