PROBLEM TO BE SOLVED : To provide an epidermal thickening inhibitor that inhibits epidermal thickening caused by ultraviolet exposure, and a cosmetic preparation, quasi drug, pharmaceutical or food and drink containing the epidermal thickening inhibitor. SOLUTION : The present invention provides an epidermal thickening inhibitor that inhibits epidermal thickening caused by ultraviolet exposure, containing Areca catechu L. (Palmae) seed extract as an active ingredient, and a cosmetic preparation, quasi drug, pharmaceutical or food and drink containing the epidermal thickening inhibitor. The cosmetic preparation is preferably in the form of skin application such as a lotion, cream, latex, cosmetic liquid. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT