A color toner (magenta toner) showing not only color image forming performances such as color reproducibility, gradation characteristic, light-fastness, full-color image forming characteristic and a chargeability but also excellent in matching with various members of an electrophotographic apparatus is produced from a binder resin, a wax component and a specific monoazo pigment composition. The monoazo pigment composition is characterized by a principal monoazo pigment of a specific structure and specified amounts of a &bgr;-naphthol derivative and an aromatic amine, usable as materials for synthesizing the monoazo pigment.