Misos were fermented using 40 kinds of rice koji gathered from different factories and activities of several enzymes contributing to the quality of the misos were analyzed by multiple regression analysis. Protease activity at pH 6. 0 (neutral protease, NP) and leucine aminopeptidase (LAP) I contributed significantly to the sensory evaluation scores of miso. NP and pectin lyase (PEL) contributed to the color evaluation of miso, and acid carboxypeptidase (ACP) II·III·IV and PEL to the color indexes, Y (%) and x. ACP II·III·IV and LAP I contributed to the taste evaluation, NP, PEL and cellulase (CMCase) to the hydrolysis of soybean protein, and NP to the liberation of glutamic acid (Glu) from the protein. The minimum activities of the main proteases necessary for the production of salty rice miso were as follows ; 50 units of NP, 60 units of protease at pH 3.0 (acid protease, AP), 5 units of protease at pH 7. 5 (alkaline protease, ALP), and 0.9 units of ACP II·III·IV per gram of rice koji, respectively. The minimum activities of α-amylase and glucoamylase necessary for the production of salty rice miso were 1, 000 and 200 units per gram of rice koji , respectively.