The present invention provides a peroxisome proliferator-activated receptor (PPAR) activator, which is free from the problem of side effects, can be taken over a long term and has no characteristics taste. Nobiletin is employed as a PPAR activator. Nobiletin has an excellent PPAR activity and has an excellent adiponectin secretion-promoting effect, and is contained in a large amount in citrus fruits, in particular, in Shiikuwasha (Citrus depressa HAYATA) indigenous to Okinawa (Japan). Since citrus fruits have been consumed for many years, the safety of nobiletin has been proven and besides, nobiletin has a low calorie content. Therefore, it can be taken over a long term. Moreover, because of being tasteless and odorless, nobiletin would not damage the unique taste of a food when added thereto. Therefore, it can be added to foods and taken.