The present invention is intended to provide acidic gel foods containing soybean protein to diversify means of taking soybean protein in daily eating habits. Using the acid-soluble soybean protein as specified in the description, an aqueous solution or an alcohol-containing aqueous solution of the protein is adjusted to pH 3 to 4.5. Then an acid having 2 or more acid groups per molecule or its salt or a salt of another acid is added thereto and the mixture is heated to form a gel. Thus, acidic gel foods including a jelly-like food favorable as a food can be obtained.