Disclosed is a simple method for producing a fine particle which is surface-modified with a water-soluble substance and contains a lipid, a fatty acid or a derivative of them. Specifically disclosed is a method for producing a fine particle surface-modified with a water-soluble substance which method includes a step wherein fine particles containing a lipid, a fatty acid or a derivative of them are present in a liquid containing a polar organic solvent in a dispersed state and a surface modifier composed of a lipid derivative, fatty acid derivative or aliphatic hydrocarbon derivative of a water-soluble substance is present in the liquid in a dissolved or dispersed state.
