The concentrations of seven non-volatile amines, tyramine (Tym), histamine (Him), phenethylamine (Phm), putrescine (Put), cadaverine (Cad), spermidine (Spd) and spermine (Spm), during miso fermentation were studied. Tym of these amines which is generally known to be present in miso was detected during fermentation by the conventional production method. Him and Phm were not detected, and concentrations of Put, Cad, Spd and Spm, which were present in the raw starting material for miso, did not change significantly during fermentation. However, Tym and Him were produced when the miso starting materials, i. e., cooked soybeans, rice koji and mashed miso, were added to liquid medium and allowed to stand. Tym- and Him- producing bacterial strains were isolated from the liquid culture media containing the miso starting materials. The Tym-producing strain was a gram-positive coccus, and the Him-producing strain was a gram-positive rod. Thus, the results show that the Tym and Him observed in culture were produced by the two different species. During miso fermentation, Tym and Him are apparently produced within a short period of time when the respective optimum conditions for their growth are present. With the exception of Phm which did not exist in the miso starting materials, other amines including Put, Cad, Spd and Spm were not produced and microorganisms producing them are not believed to be present during miso fermentation.