An object of the present invention is to provide an anti-obesity agent, or to provide foods and drinks, food and drink additives, and feeds or feed additives for anti-obesity. In order to achieve such an object, the present invention provides an anti-obesity agent comprising hydroxyproline or an N-acyl derivative of hydroxyproline or a pharmaceutically acceptable salt thereof or foods and drinks, food and drink additives, feeds or feed additives for anti-obesity comprising the same.