An image forming apparatus and a control method for the same, which ensure acquisition of a high-quality image by controlling physical-states of toner on a developer roller based on sensed variation in states of internal components of a developer cartridge, and which enable sensing and determination of the lifespan of the developer cartridge, is provided. The control method for the image forming apparatus includes applying a current detection bias to a developer roller blade of a developer cartridge, detecting the magnitude of current of the developer roller blade when the current detection bias is applied to the developer roller blade, and variably controlling a developer cartridge bias to be applied to the developer cartridge for image formation based on the detected magnitude of current of the developer roller blade, so as to allow a target magnitude of constant current to flow through the developer roller blade during image formation.