The present report deals with the relation between formation of proteinase or amylase and the osmotic value in Aspergillus awamori. Proteinase is scarcely formed before the osmotic value falls down to the critical value such as 1.3-1.2M of sucrose. The critical osmotic value in the case of the surface culture is larger than that in the case of the submerged culture. In the latter culture, proteolytic activity can be measured only after the osmotic value decreases to 1.2M. The osmotic value of the completely washed mycelium is 1.0M and increases to 1.1M after 20hrs. incubation. But proteolytic activities in these cases differ as their ages as shown in the table. By washing the mycelium with NaCl solution of various concentrations, it was found that the optimum osmotic value for proteinase formation was 1.1-1.0M and the same conclusion was valid for α-amylase formation.