An image forming apparatus includes a developing unit that contains an electrostatic charge image developer and develops an electrostatic charge image formed on the surface of an image holding member as a toner image by using the developer, wherein the developer contains a carrier and an electrostatic charge image developing toner that includes a toner particle and an external additive, the toner particles have an average circularity of from 0.98 to 1.00 and a number-particle diameter distribution index (lower GSD) on a small diameter side of 1.22 or more and contain at least a vinyl resin, and the external additive contains silica particles having a compression aggregation degree of 60% to 95% and a particle compression ratio of 0.20 to 0.40.