According to one embodiment, an image forming apparatus includes an identification-section detecting device configured to detect, on the basis of an identification section included in a developer cartridge, a type of a developer stored by the developer cartridge and detect, on the basis of an identification section included in a developing device, a type of a developer used by the developing device and a control section configured to determine, on the basis of an output of the identification-section detecting device, whether the type of the developer stored by the developer cartridge and the type of the developer used by the developing device coincide with each other, prohibit from performing image formation if the types of the developers do not coincide with each other, and set an image forming method according to the determined types of the developers if the types of the developers coincide with each other.