Abstract: The present invention provides, as a composition that is highly safe and superior in preservative properties, comprising (a) a xanthine, (b) a buffer and (c) at least one member selected from sorbic acid, EDTA, and salts thereof. This composition has superior preservative properties so that it inhibits the generation and proliferation of microorganisms even when stored for a long period of time. Furthermore, the present invention provides a method for enhancing the preservative properties of sorbic acid, EDTA, and salts thereof, which are known to have preservative properties, and the preservative properties of compositions containing these ingredients, and provides a method for producing a composition with superior preservative effectiveness.