The object of the present invention is to provide a composition maintaining a blood coenzyme Q concentration at a high level in blood for a prolonged period of time, in order to surely attain an effect of coenzyme Q, which can be expected to manifest a superior effect in maintaining health in humans and animals.By using a composition which comprises a coenzyme Q being a mixture of a reduced coenzyme Q and an oxidized coenzyme Q with the proportion of the reduced coenzyme Q to the whole coenzyme Q of more than 95% by weight, the present invention can attain a high maximum blood concentration of a coenzyme Q as well as long maintenance of high concentration of coenzyme Q in blood for a prolonged period of time, and the area under the blood concentration curve (AUC) can be expanded.