A color toner, a developer, a developing device for performing development by using the developer and an image forming apparatus having the developing device are provided. A developer, which contains a color toner formed by adding zinc oxide particles externally to the surfaces of toner base particles containing binder resin and colorant, in which the average primary particle size of zinc oxide particles falls in a range of 10 nm or more and 50 nm or less, the average particle size of primary-particle aggregates of zinc oxide particles is 0.3 μm or less and the zinc oxide particle is made of zinc oxide doped with aluminum, is charged in a developer tank of a developing device of an image forming apparatus for image formation.