A developer includes the following components: the magnetic particles of the surface covering layer on at least one part of the surface and the magnetic particle is composed of organic matter, the pigmented particles which is provided with the exterior additive on the surface of the mother particle that at least includes resin and colorant, and the electrification of the additive is weaker than the surface covering layer of the magnetic particle, thereby, the developer has high transfer efficiency and can get the picture with high quality.