The present invention provides a composition of a practically usable solution capable of stably maintaining, against oxidation, reduced coenzyme Q, which has not been employed in practice so far because of being liable to undergo oxidation and hydrophobic, a method of preparing the solution and a method of storing the solution. A solution of reduced coenzyme Q which can be stored at a low temperature or room temperature over a long time can be prepared by coating reduced coenzyme Q with liposome made of refined soybean lecithin, etc, and solubilizing, or solubilizing or emulsifying reduced coenzyme Q by using a surfactant at a low temperature.
