As the binder resin for the toner to be used in the present invention, there may be employed homopolymers of styrene and its derivatives and copolymers thereof such as polystyrene, poly-p-chorostyrene, polyvinyltoluene, styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer; copolymers of styrene and acrylic acid ester such as styrene-methyl acrylate copolymer, styrene-ethyl acrylate co