PURPOSE: To prepare a plum vinegar essentially free from salt, by the acetic acid fermentation of a mixture of plum fruit juice and ethanol.

CONSTITUTION: Well-ripened plum fruit is crushed together with its stone optionally in the presence of a proper amount of water, and squeezed to obtain a plum juice. The juice is mixed with 5W30wt%, preferably 10W20wt% of ethanol or an ethanol-containing liquid, in terms of pure ethanol, added with bacteria belonging to acetobacter, and fermented under aerobic condition at 10W50°C for several days W several weeks. If necessary, the obtained stock liquid is filtered to obtain a concentrated salt-free plum vinegar having an acidity of about 10W15%.