Brevibacillus choshinensis is characterized in that its extracellular proteolytic activity is extremely low and its protein secretion productivity is excellent, but it is desired that not only the extracellular proteolytic activity of the strain is further reduced but also the intracellular proteolytic activity thereof is further reduced. When Brevibacillus choshinensis is used as a host for the production of protein pharmaceuticals and the like, it is also desired that it does not form spores and is readily sterilized. The above problems have been solved by inactivating the sporulation-associated gene thereof and by cloning and inactivating the extracellular and intracellular protease genes thereof.