Patent ID: 8168360

Claim:
An external additive, containing oxide fine particles as a main component, added to a toner used in an electrophotographic image forming apparatus, dimethylsilyl groups being introduced to surfaces of the oxide fine particles, and the oxide fine particles being subjected to a heating treatment after the dimethylsilyl groups have been introduced to the surfaces of the oxide fine particles, so that an amount of octamethylcyclotetrasiloxane volatilizing in a first volatilizing test is 0.2 μg or less, the first volatilizing test being performed in such a manner that 2 g of the external additive whose oxide fine particles have been subjected to the heating treatment is contained in a sealing container and an inside of the sealing container is kept at 120° C. for 10 minutes so that octamethylcyclotetrasiloxane volatilizes from the external additive.