Provided is a process cartridge integrally supporting an electrophotographic photosensitive member, a developing unit, and a cleaning unit, and being detachably attachable onto a main body of an electrophotographic apparatus. A surface layer of the electrophotographic photosensitive member comprises a polycarbonate resin having a structural unit represented by the formula (1), a structural unit represented by the formula (2), and a structural unit represented by the formula (3). Toner contains: a toner particle containing a resin; and an external additive. The external additive contains a particle of a silicon atom-containing compound, and a content ratio of the particle of the silicon atom-containing compound in the toner is 2.0 to 3.0 mass % with respect to a total mass of the toner. Also provided is an electrophotographic apparatus including the process cartridge.

The toner has a toner matrix particle containing a crystalline polyester resin. Associated silica including two or more of primary particles is present on the surface of the toner matrix particle. The coverage with associated silica onto the toner matrix particle is 1% or more to 30% or less, and the adherence strength of associated silica to the toner matrix particle is 20% or more to 90% or less.

In a two-component developer, toner particles include toner mother particles and external additive particles including strontium titanate particles. A first percentage content being a percentage content of the strontium titanate particles to the mass of the toner mother particles is 0.30-0.90% by mass. The carrier particles include carrier cores and coat layers. The coat layers contain barium titanate particles and a coating resin including a silicone resin. The barium titanate particles have a number average primary particle diameter of 100-500 nm. A second percentage content being a percentage content of the coat layers to the mass of the carrier cores is 2.0-4.0% by mass. A third percentage content being a percentage content of the barium titanate to the mass of the coating resin satisfies formula (1) (X?10)?Z?45.0. In formula (1), X represents the first percentage content and Z represents the third percentage content.

The external additive for toner includes an external additive particle containing: a fine particle A; and a plurality of fine particles B that are each present so as to partially protrude from a surface of the fine particle A, wherein the fine particle A (i) is a particle of an organosilicon compound having a siloxane bond, (ii) has a number-average particle diameter of 0.03 ?m or more and 0.30 ?m or less, and (iii) has an average circularity of 0.90 or more, wherein, when the number-average particle diameter of the fine particle A is represented by D.sub.A, and a number-average particle diameter of the plurality of fine particles B is represented by D.sub.B, D.sub.B/D.sub.A is 0.10 or more and 0.63 or less.

An external additive for toner comprising: a fine particle A containing, as a binder component, an organosilicon compound having a siloxane bond; and a fine particle B that is present on a surface of the fine particle A in a state of being at least partially embedded in the surface of the fine particle A, wherein the external additive for toner (i) has a number-average particle diameter of a primary particle of 0.03 ?m or more and 0.30 ?m or less, and (ii) has a Young's modulus of 10 GPa or more and 30 GPa or less, wherein content ratios, on a number basis, of the following unit (a), unit (b), and unit (c) in the fine particle A based on all silicon atoms present in the fine particle A satisfy the following expressions (1) and (2).

(a)+(b)+(c)?0.80(1)

(b)+(c)?0.30(2)

##STR00001##

A toner includes toner particles containing a crystalline organic material that contains a crystalline vinyl resin as an essential component and a crystalline polyester and a wax component as optional components. A total of the crystalline vinyl resin, crystalline polyester, and wax component with respect to the toner particles is 10.0 to 90.0 mass %. The crystalline vinyl resin contains a crystalline resin A having (i) units A and (ii) units B. The toner particles contain 0.0020 to 0.0500 mass % of a metal that can form a complex with an acetylacetonate moiety in a unit B of the crystalline resin A with respect to a mass of the toner particles. The acetylacetonate moiety of at least one of the units B in the crystalline resin A forms a complex with the metal. In the crystalline resin A, a content of the unit B is 0.50 to 10.0 mass %.

An image forming apparatus is characterized by that a region of the surface of an image bearing member in which a second potential difference that generates an electrostatic force such that developer which is charged to an opposite polarity to the normal charging polarity of the developer moves from the image bearing member to a developer bearing member was generated in a second operation that moves the developer from the surface of the image bearing member to the developer bearing member includes a region where a first potential difference that generates an electrostatic force such that the developer which is charged to an opposite polarity to the normal charging polarity of the developer moves from the charging member to the image bearing member was generated in a first operation that moves the developer from the surface of the charging member to the surface of the image bearing member.

An image forming apparatus is characterized by that a region of the surface of an image bearing member in which a second potential difference that generates an electrostatic force such that developer which is charged to an opposite polarity to the normal charging polarity of the developer moves from the image bearing member to a developer bearing member was generated in a second operation that moves the developer from the surface of the image bearing member to the developer bearing member includes a region where a first potential difference that generates an electrostatic force such that the developer which is charged to an opposite polarity to the normal charging polarity of the developer moves from the charging member to the image bearing member was generated in a first operation that moves the developer from the surface of the charging member to the surface of the image bearing member.

A toner includes a toner particle containing a binder resin and an external additive. A fragment peak derived from a boron atom and a fragment peak derived from a boron-oxygen structure are detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurement of the toner. The toner particle contains dodecylbenzenesulfonic acid or a dodecylbenzenesulfonic acid salt. Hydrotalcite is contained as the external additive.

An image forming system that forms an image on a continuous sheet using an electrostatic charge image development toner. The electrostatic charge image development toner includes a toner base particle including a binder resin and a brilliant pigment having a coating layer containing an inorganic element.