Water extract of mulberry tree barks(Morus alba Linne) was studied for its proteolytic activity. Protein content of the extract was 1.12mg/ml and its specific activity was 5.14U/ml. The enzyme was active on various proteins : the relative acitities were 100 for casein, 63 for albumin, 58 for collagen, 45 for hemoglobin and 36 gelatin, respectively. There suggested that the ability of the enzyme to hydrolyze meat was relatively high since those are major meat proteins. Optimum pH and temperature for proteolytic activity were : pH 6.0 and 6$0^{circ}C$. And the enzyme was stable at the pH range of 6.0 to 7.0 and temperature between 50 and 8$0^{circ}C$. Apparent proteolytic activities could support some scientific grounds of traditional application of mulberry tree barks to home cooking for meat tenderization.