A toner comprising: a toner particle comprising a binder resin; and an external additive on a surface of the toner particle, wherein the binder resin comprises a resin having an ester bond, a peak corresponding to boric acid is detected in ATR-IR analysis of the toner particle in an ATR method using germanium as an ATR crystal, and when a dispersed solution obtained by dispersing the toner in an aqueous solution containing a surfactant is subjected to a detachment treatment A including shaking for 300 seconds using a shaker, and when an external additive detached from the toner by the detachment treatment A is denoted as external additive A, a charge amount of the external additive A using a standard carrier (F81) is −0.5 μC/g or less.

A toner comprising: a toner particle comprising a binder resin and boric acid; and an external additive A having a primary particle major diameter of 80 to 200 nm, wherein in ATR-IR analysis of the toner particle in an ATR method using germanium as an ATR crystal, a peak corresponding to boric acid is detected, the average value of a shape factor SF-1 of the external additive A is 105 to 250, and the average value of a shape factor SF-2 of the external additive A is 102 to 250.

A toner comprising a toner particle, and an external additive on a surface of the toner particle, wherein the external additive comprises an agglomerate of fine silica particles surface-treated with silicone oil; when a number-average particle diameter of the agglomerate of the fine silica particles is defined as Rb, the Rb is 12 to 80 nm; when an integrated value of a D unit is defined as A, which obtained when an integrated value of a Q unit is set to 100 in a CP/MAS measurement in a .sup.29Si-solid-state NMR of the fine silica particles, the A is 120 to 300, and the agglomerate of the fine silica particles has a coefficient of variation of particle diameters of 1.00 to 3.00, based on a number of the agglomerate of the fine silica particles.

A toner includes: toner base particles including a binder resin, a colorant, an inorganic filler, and a release agent; and an external additive. An average circularity of the toner is 0.974 or more but 0.985 or less. A surface roughness parameter Sz of a surface of the toner is 200 nm or more but 500 nm or less, the surface roughness parameter Sz being measured with an atomic force microscope (AFM).

A developing device includes a developing container, a first stirring conveyance member, a second stirring conveyance member, and a developer carrying member. The developing container includes a first conveyance chamber and a second conveyance chamber that are arranged mutually side by side, and contains a two-component developer including a carrier and a toner. The first stirring conveyance member stirs and conveys the developer present in the first conveyance chamber in a first direction. The second stirring conveyance member stirs and conveys the developer present in the second conveyance chamber in a second direction. The developing container includes a toner replenishment portion that directly feeds a replenishment toner into the developer present in the first conveyance chamber from an upstream side of the first conveyance chamber with respect to the first direction. The carrier satisfies 0.73≤FR×AD/shape factor≤2.10.

Provided is a hydrophobic silica powder that can be obtained by the sol-gel process, and that is excellent in charge properties. The hydrophobic silica powder has a hydrophobicity of 50% or more, a saturated water content of 4% or less, and a nitrogen content of 0.05% or more.

An electrophotographic apparatus forms an image by forming an electrostatic latent image on the surface of an electrophotographic photoconductor and transferring a toner developed in the electrostatic latent image to a transfer material, where the photoconductor includes an outermost layer containing a silica filler, where the toner includes a toner base particle and an external additive as components, where the toner base particles at least contains a binder resin, a colorant, and a mold lubricant, and where the external additive represents externally-added silica and externally-added fine powder, the externally-added fine powder having the surface of a core hydrophobized with a silane compound, the core being derived by addition of silica to strontium titanate.

A toner includes toner particles. The toner particles each include a toner mother particle and an external additive attached to the surface of the toner mother particle. The external additive contains specific external additive particles and silica particles. The specific external additive particles each include a base containing barium titanate and a coat layer covering the base. The coat layer contains antimony tin oxide. Mass ratios of metal elements contained in the toner particles satisfy 0.10<(Ba/Si)<0.60 (formula (1)); 0.05<(Ba/Si)<0.20 (formula (2)); and 1.5<(Sn/Ba)<5.0 (formula (3)).

An electrostatic image developing toner includes toner particles including a binder resin and a release agent, an external additive A, and an external additive B. At least the external additive A is present on the surface of the toner particles. At least the external additive B is present on the external additive A. The external additive B is an aggregate of two or more particles. The toner particles have an average circularity of 0.8 or more and 0.94 or less. The amount of the release agent present at the surface of the toner particles is 5 area % or more and 30 area % or less based on the total surface area of the toner particles.

Provided is a two-component developer for electrostatic charge image development including: toner particles containing toner base particles and an external additive disposed on a surface of the toner base particles; and carrier particles having a core material particle and a shell portion disposed on a surface of the core material particle, wherein the external additive contains inorganic particles surface-modified with a surface modifier represented by the following Formula (1); and a value of an iron element content (atomic %) measured by X-ray photoelectron spectroscopy (XPS) on a surface of the carrier particles satisfies the following Expression (1),

(R.sub.1).sub.4-n—Si—(X).sub.n  Formula (1):

4.0≤{A.sub.Fe/(A.sub.c+A.sub.o+A.sub.Fe)}×100≤15.0  Expression (1):