The present invention has its object to provide a safer and highly effective composition capable of relieving or preventing xerostomia. The present invention relates to an agent for relieving or preventing xerostomia comprising an oxidized coenzyme Q and/or a reduced coenzyme Q as active ingredients, a composition containing the agent for relieving or preventing xerostomia in a form of a food product, a health food, a dietary supplement, a supplement, an oral health care product, a medicament, a quasi drug, a pet food, a feed or the like, and a method for treating xerostomia and a method for reducing risks of xerostomia comprising administering the composition.