PURPOSE: To sufficiently elute mineral substances contained in seaweeds and produce seaweed vinegar, having flavor and taste of the seaweeds added thereto, by subjecting a mixture of the seaweeds with a fermentative saccharide substance to alcoholic and acetic acid fermentation.

CONSTITUTION: A saccharide liquor, such as a saccharified liquor, obtained by hydrolyzing starch and containing fermentative saccharide substances is blended with seaweeds,such as red or brown algae, in a dry state in an amount of 1W3wt.% based on the saccharide liquor to provide a fermentation raw material. An alcoholic fermentation yeast and acetic acid bacteria are then added to the resultant fermentation raw material to carry out alcoholic and acetic acid fermentation. The obtained fermentation liquor is subsequently filtered.