The present invention is capable of alleviating or preventing xerostomia, and an object thereof is to provide a safer and compositions having excellent efficacy. The present invention contains oxidized coenzyme and enzyme Q and / or reduced coenzyme Q to the active ingredient, characterized in that it contains, alleviation or prophylactic agent for xerostomia, the moderate sum or prophylactic agent, the food, health foods, nutraceuticals, supplements, oral cavity health care products, pharmaceuticals, quasi-drugs, pet food or a composition of such feed, as well as of xerostomia, which comprises administering the composition on how to reduce the risk of treatment methods and xerostomia.