Spherical toners having excellent fusibility are disclosed. The toners are fusible at low temperatures and are excellent in preservability and therefore charge properties, flowability, and transferability do not deteriorate. The toners contain a colorant and a nitrogen-containing polyester resin, in which the concentration of nitrogen at the surface of toner particles is higher than the concentration of nitrogen of the entire particles. The ratio of the surface concentration to the overall concentration is from 1.2 to 10. Additionally, the nitrogen-containing resin is preferably a polyester resin modified by urea bonds. Also, it is preferred that the toner particles are substantially spherical having an average sphericity E of from 0.90 to 0.99.