PROBLEM TO BE SOLVED: To provide a stable and inexpensive lipase inhibitor of high safety, excellent in prophylactic and ameliorative effects and curing effect for pimples caused by normal bacteria flora on the skin such as acne bacteria and excellent in the prophylactic and ameliorative effects and curing effects for lifestyle-related diseases including obesity, hyperlipemia and diabetes each induced by high-fat meals in daily life.SOLUTION: The lipase inhibitor includes 1-isomangosteen as an active ingredient. Besides, cosmetics, food/drink compositions and pharmaceutical compositions each containing the lipase inhibitor are also provided.