[PROBLEMS] To improve the activity of a Koji mold protease in a solid or liquid culture medium in the production of foods (e.g., a seasoning agent), pharmaceuticals (e.g., a digestive agent), proteases for use in detergents and the like. [MEANS FOR SOLVING PROBLEMS] Disclosed are: a recombinant vector capable of increasing the secretion of a Koji mold protease; a Koji mold which is transformed with the vector and has an increased expression of a gene for a protease/an increased secretion of a protease; a method for production of a protease by using a transformed Koji mold; and others.