Abstract: It is an object of the present invention to provide an extraction method for a sialic acid-containing compound from a natural raw material, which has no risk of contamination with pathogens affecting animals, can achieve mass production, and does not require the use of an organic solvent harmful to the environment and human body. Provided is an extraction method for a water-soluble sialic acid-containing compound, the method comprising: crudely extracting a water-soluble component with water, polyol, or water containing either an acid or an alkali or polyol from a plant body or a processed product of the plant body, in particular, seeds of cereal or seeds of bean; and separating and recovering the water-soluble sialic acid-containing compound from the resultant crude extract solution with a column packed with a serotonin affinity support.