Persimmon vinegar was produced from persimmon fruits of inferior grade. Crushed fruits were fermented by adding yeasts directly (Expt. No.1), or after sterilization (Expt. No.2) at 70°C and pH 4. 6, followed by acetic acid fermentation with bacteria. Acetic acid concentration reached 58.3 g/l after 30 days in No.1, and 62.2 g/l in No.2 after 120 days. Polyphenols present in persimmon juicewas decreased during alcoholic fermentation, and further in acetic acid fermentation. The persimmon vinegar produced contained more potassium than commercial vinegar on the market, but ascorbic acid content was about the same as the latter. Procuction of persimmon vinegar was also examined by a continuous membtane-filtration reactor in a closed system which was connected to pure oxygen supplier (Expt. No.3). As to the organic acids contents, the vinegar in No.1 contained only small amounts of acids except lactic acid, but inverse was the case in No.2 and 3. Vinegars in No.2 and 3 contained more malic citric and succinic acids than the one on the market. No.3 contained more aroma components such as acetaldehyde. ethyl acetate, isobutyl alcohol and isoamyl alcohol than No.1 or 2.