A potent fungus for blood-coagulating enzyme was isolated from soil during screening tests of about 1500 strains of microorganisms. The fungus was identified as a strain belonging to Cephalosporium. This enzyme could be produced effectively by solid culture on wheat bran and partially purified to about 800 fold. This enzyme was one of the alkaline proteases. It was stable over a pH range of 7~10 and was activated by Ca2+ The enzyme could not coagulate 1% fibrinogen solution. The enzyme mixed with diluted blood plasma coagulated the fibrinogen solution. The enzyme also coagulated the citrated plasma from humans, bovines, mice, goats and hens.