An electrostatic charge image developing carrier includes: magnetic particles; and a resin layer coating the magnetic particles and containing inorganic particles, in which an average particle diameter of the inorganic particles is 5 nm or more and 90 nm or less, an average thickness of the resin layer is 0.6 μm or more and 1.4 μm or less, and a ratio B/A of a surface area B of the electrostatic charge image developing carrier to a plan view area A of the electrostatic charge image developing carrier is 1.020 or more and 1.100 or less when a surface of the electrostatic charge image developing carrier is three-dimensionally analyzed.

A toner includes toner particles. The toner particles each include a toner mother particle and an external additive provided on the surface of the toner mother particle. The toner mother particles contain a binder resin and a magnetic powder. The external additive includes alumina particles. The alumina particles have a number average primary particle diameter of at least 150 nm and no greater than 400 nm. The toner has a time constant of at least 1.0 seconds and no greater than 10.0 seconds. A sediment has a zeta potential at pH 2 of at least 0.0 mV and no greater than 20.0 mV. The sediment is obtained by separation from a dispersion of the toner.

A toner is provided. The toner comprises colored particles and external additives present on surfaces of the colored particles. The colored particles each comprise a core and a shell layer. The core contains a crystalline resin, a non-crystalline resin, and a colorant. The shell layer contains a resin and has a thickness of from 30 to 130 nm. The external additives comprise a metal oxide and a silicon compound. An electronegativity X(A) of the metal oxide and an electronegativity X(Si) of the silicon compound satisfy a relation 0.5≤X(A)/X(Si)≤0.8. A proportion of an amount of the metal oxide directly adhered to the surfaces of the colored particles to a total amount of the metal oxide present on the colored particles is from 60% to 90% by mass.

A magnetic toner comprising a magnetic toner particle including a binder resin, a magnetic body and a crystalline polyester, wherein in cross-sectional observation of the magnetic toner particle using a transmission electron microscope, a variation coefficient CV3 of an occupied area ratio of the magnetic body when a cross section of the magnetic toner particle is divided by a square grid having a side of 0.8 μm is from 40.0% to 80.0%, and assuming that a storage elastic modulus at 40° C. is taken as E′(40) [Pa] and a storage elastic modulus at 85° C. is taken as E′(85) [Pa], the storage elastic moduli being obtained in a powder dynamic viscoelasticity measurement of the magnetic toner, the following formulas (1) and (2) are satisfied.
E′(85)≤2.0×10.sup.9  (1)
[E′(40)−E′(85)]×100/E′(40)≥70  (2)

A toner is provided, which has a toner particle that contains a binder resin, and organosilicon polymer particle on a surface of the toner particle. A methanol concentration a (vol %) of the organosilicon polymer particle in a wettability test and a methanol concentration b (vol %) of the toner particle in a wettability test satisfy Expression (I) below:
|a−b|≤25  (I), and an adhesion index of the organosilicon polymer particle on a polycarbonate film, calculated on the basis of Expression (II) below, is not more than 3.5:
Adhesion index=area ratio c of the organosilicon polymer particle having migrated to the polycarbonate film/coverage ratio d of the organosilicon polymer particle on the surface of the toner particle×100  (II).

A toner for developing an electrostatic charge image contains toner particles containing at least one binder resin; the Mg element in an amount such that in an x-ray fluorescence analysis of the toner, the net intensity of the peak for the Mg element is 0.10 kcps or more and 1.20 kcps or less; and at least one external additive including particles of at least one compound represented by formula (1),
MTiO.sub.3  (1)
where M represents at least one selected from the group consisting of Ca, Sr, and Ba.

An electrostatic charge image developing carrier includes a magnetic particle and a coating resin layer that covers the magnetic particle, and an amount of the coating resin layer that is peeled off from the magnetic particle when the carrier dispersed in water is irradiated with ultrasonic waves, relative to a coating amount of the coating resin layer before ultrasonic irradiation, is 800 mass ppm or more and 2,000 mass ppm or less, and a difference between an initial coating amount of the coating resin layer of a carrier having no travel history and a coating amount of the coating resin layer of a carrier having a travel history and being taken out from an electrostatic charge image developer, relative to the initial coating amount of the coating resin layer, is 0 mass ppm or more and 3,000 mass ppm or less.

The present invention provides: a ferrite carrier core material for an electrophotographic developer, the material having a mesh passing amount of 3 wt % or less as indicated by the ratio of the weight of particles passing through a 16 μm-mesh to the weight of whole particles constituting a powder, and having a particle strength index of 2 wt % or less as indicated by a difference between the mesh passing amounts before and after crushing; a ferrite carrier which is for an electrophotographic developer and in which the surface of the ferrite carrier core material is coated with a resin; and an electrophotographic developer which includes the ferrite carrier and a toner.

A magnetic toner comprising a toner particle comprising a binder resin and magnetic iron oxide particles, wherein a content of the magnetic iron oxide particles in the magnetic toner is 30 to 45 mass %, the magnetic iron oxide particles contain (i) spherical magnetic iron oxide particles and (ii) at least one selected from the group consisting of hexahedral magnetic iron oxide particles and octahedral magnetic iron oxide particles, and a content of the spherical magnetic iron oxide particles in the magnetic iron oxide particles is 1.0 to 9.0% by number.

A developing device including: a developer; and a developing member configured to carry the developer on a surface thereof, the developing roller including an electro-conductive substrate and a single-layer elastic layer serving as a surface layer on the substrate, the surface layer comprising a binder resin, and the binder resin contains a crosslinked urethane resin and a crosslinked acrylic resin, the crosslinked urethane resin and the crosslinked acrylic resin form an interpenetrating polymer network structure in a first region from an outer surface of the surface layer to a position at a depth of 0.1 μm from the outer surface, wherein the developer contains developer particles each containing at least a binder resin and a magnetic substance.