<p>[PROBLEMS] To provide a drug delivery system which is retained in the circulating blood and enhances the efficacy of a drug in the target organ or cells. [MEANS FOR SOLVING PROBLEMS] A drug-containing liposome for therapeutic use which comprises a liposome prepared by employing polyethylene glycol cholesteryl ether as a part of a liposome-forming base and using this liposome-forming base. By further employing polyethylene glycol diacyl glycerol ester as a part of the liposome-forming base, a favorable drug efficacy can be obtained.</p>
