The present invention relates to a nanocapsule composition and its toner composition for thermosensitive rewritable recording media, more particularly to a core/shell-type nanocapsule composition for thermosensitive rewritable recording media, which has fine capsule of a few nanometers in size and superior recording property and heat stability, a preparation method thereof and its toner composition for thermosensitive rewritable recording media. The toner composition according to the present invention is suitable for high-resolution electrostatic image toner, paper and film. Also, it enables reuse of recording media because the recording is erased when the media (e.g.: paper and OHP film) is heated to a high temperature.