Sulfated fucogalactan or its salt useful as a reagent for sugar chain engineering or an HGF-production inducer; a degraded product or its salt obtained by treating the sulfated fucogalactan with a sulfated fucogalactan digesting enzyme; the sulfated fucogalactan digesting enzyme useful in sugar chain engineering; a process for producing the degraded product by treating sulfated fucogalactan or its salt with the above enzyme; and a process for producing the sulfated fucogalactan digesting enzyme.