The present invention has its object to provide a solid preparation containing reduced coenzyme Q10 with high stability by protecting reduced coenzyme Q10 against oxidization to oxidized coenzyme Q10 by molecular oxygen.The present invention providesa solid preparation containing reduced coenzyme Q10which comprises a solid composition containing reduced coenzyme Q10 coated with at least one coating medium selected from among oil-soluble coating media and water-soluble coating media.The present invention also providesa method for stabilizing a solid preparation containing reduced coenzyme Q10,wherein a solid composition containing reduced coenzyme Q10 is coated with at least one coating medium selected from among oil-soluble coating media and water-soluble coating media to thereby stabilize the resulting solid preparation containing reduced coenzyme Q10.
