Polymer toner and method of production thereof

A polymerized toner of core-shell structure, comprising core particles composed of colored polymer particles which contain a compound having at least one >C=N+< structure in its molecule and a colorant, and a layer of a polymer having a glass transition temperature higher than that of a polymer component making up the core particles, said polymer layer covering each of the core particles, a production process thereof, an image forming process comprising using the polymerized toner, and an image forming apparatus containing the polymerized toner.