A toner whose flowability, chargeability and fixing property are enhanced, a developer, a developing device and an image forming apparatus are provided. The toner comprises a toner particle in which a shell layer is formed on a surface of a core particle, and external additive, where (1) the shell layer is formed in a film on the surface of the core particle, (2) a shape factor SF-2 is 120 or more and 140 or less, and (3) a BET specific surface area measured by the BET method is 1.2 m2/cm3 or more and 4.0 m2/cm3 or less. The developer containing such a toner is filled into the developing device in the image forming apparatus in order to form an image.