Patent ID: 8728691

Claim:
An image forming apparatus, comprising: a developer tank that houses a two-component developer containing toner and carrier; and a supply unit that supplies the developer tank with supply developer containing toner and carrier, wherein the toner contained in the two-component developer contains toner mother particles, and inorganic fine particles that are externally added to the toner mother particles, the toner contained in the supply developer contains toner mother particles, and inorganic fine particles that are externally added to the toner mother particles, the inorganic fine particles are silicon dioxide particles, the toner contained in the two-component developer is the same as the toner contained in the supply developer, the carrier contained in the two-component developer is identical to the carrier contained in the supply developer with respect to composition, but has been treated to have a rougher surface, and wherein, when the ratio of mass of inorganic fine particles attached to the carrier contained in the two-component developer to mass of the carrier contained in the two-component developer is A, and the ratio of mass of inorganic fine particles attached to the carrier contained in the supply developer to mass of the carrier contained in the supply developer is B, the following Formula (I) is satisfied: 0.7 <B/A< 0.96 (1).