A deterioration preventing agent excellent in deterioration preventing effect on foods, cosmetics or the like is provided. The deterioration preventing agent comprising a compound whose dynamic hydration number is 25 or higher such as malto-triose . A preferred deterioration preventing agent further contains a water-soluble antioxidant such as rosmarinic acid, vitamin C, ascorbic acid, isoascorbic acid, a salt thereof (for example, an alkali metal salt, an alkaline-earth metal salt or the like), a catechin or a catechin-containing extract derived from a natural substance.
