A Maillard reaction inhibitor which effectively inhibits the progress of a Maillard reaction in a living body, can be safely applied without adverse side effects, can be manufactured without any complicated process, a skin anti-aging agent, an anti-diabetic complication agent and foods and beverages using the same. The Maillard reaction inhibitor contains 50 to 90% by mass of polyphenol as an active ingredient. The Maillard reaction inhibitor has a potent Maillard reaction inhibitory activity in a living body and allows for the prevention and improvement of the various dysfunction of protein in a living body. Due to this activity, the Maillard reaction inhibitor suppresses aging and can prevent and/or treat diabetic complications. Furthermore, when the above-described tannin is mixed in foods and beverages containing collagen, it is possible to suppress the Maillard reaction in the foods and beverages to suppress the deterioration of the foods and beverages.