[PROBLEMS] To provide an effective means for the prevention of or treatments for diseases attributable to lipase activity and to provide a lipase inhibitor, fat absorption inhibitor, fat accumulation inhibitor, medicinal composition, food and beverage, and cosmetic preparation which each can be the means for treatments. [MEANS FOR SOLVING PROBLEMS] The lipase inhibitor comprises a powder of leaves of hardy rubber trees or an extract therefrom obtained with water. The medicinal composition, food, beverage, cosmetic preparation, etc. have a lipase inhibitory effect.