An object of the present invention is to provide a drug delivery carrier that is free from the drug leakage problem and has an easily controllable particle size, and that can be used to deliver water-soluble drugs such as genes and proteins in a wide range of applications, including delivery of water-soluble drugs that do not have high anionic properties, and also can be used as a non-viral gene vector. The invention also provides a process for production of such drug delivery carriers. The drug delivery carrier of the present invention includes a water-soluble drug double-coated with two types of inner and outer surfactants 1 and 2.
