The object is to provide a useful fermentation product of a grape skin/seed by a lactic acid bacterium by using at least one of a grape skin and a grape seed, and also provide a pharmaceutical agent or food which can treat, ameliorate or prevent a condition associated with metabolic syndrome such as type-II diabetes, hyperlipemia and obesity effectively and safely or a pharmaceutical agent or food which is effective and safe for the whitening or anti-aging of the skin, by using the fermentation product. Specifically disclosed are: a fermentation product of a grape skin/seed by a lactic acid bacterium, which is produced by fermenting at least one of a grape skin and a grape seed with a lactic acid bacterium； and a pharmaceutical agent or food comprising the fermentation product.
