A magnetic carrier comprising a magnetic carrier core and a resin coating layer formed on the surface of the magnetic carrier core, wherein the resin coating layer includes a polymer having a structure represented by the following formula (1), and a content ratio of the structure represented by the formula (1) is from 5% by mass to 95% by mass based on a resin component of the resin coating layer, ##STR00001##
wherein, R.sup.1 is H or CH.sub.3, and X is a structure represented by the following formula (2):
(C.sub.mH.sub.2m)R.sup.2(C.sub.nH.sub.2n)OH(2)
wherein, R.sup.2 is a hydrocarbon group being a cyclic structure having 4 to 8 carbon atoms, and m and n are integers of 0 to 4.

An electrophotographic developer is provided. The electrophotographic developer comprises a toner and a carrier. The toner contains alumina particles. The carrier comprises a core particle and a resin layer coating a surface of the core particle. The carrier has a volume average particle diameter (Dv) of from 45 to 70 m and a bulk density of from 2.1 to 2.5 g/cm.sup.3.

To provide a two-component developer for electrostatic charge image development, the two-component developer enabling a high image quality to be kept and enabling the occurrence of fogging to be suppressed even in continuous printing of an image high in coverage rate. The two-component developer for electrostatic charge image development includes a toner particle including a toner base particle and an external additive disposed on the surface of the toner base particle, and a carrier particle including a core material particle and a covering section disposed on the surface of the core material particle, wherein the external additive includes an alumina particle, and the percentage of exposed area of the core material particle is 4.0% or more and 15.0% or less.

A magnetic carrier comprising a magnetic carrier particle having a magnetic carrier particle having a magnetic carrier core particle and a resin coat layer formed on the magnetic carrier core particle surface, and inorganic fine particles A present on a surface of the magnetic carrier particle, wherein each of the inorganic fine particles A has a rectangular parallelepiped particle shape, the inorganic fine particles A have D1 of 10 to 60 nm, the inorganic fine particles A are inorganic particles which have been surface treated with a surface treatment agent or silane coupling agent-treated particles, SP1 of the resin coat layer and SP2 of the surface treatment agent satisfies SP1SP214.00, and the coverage ratio of the magnetic carrier surface by the inorganic fine particles A as measured by ESCA is 5.0 to 20.0 atom %: and a two-component developer comprising at least the magnetic carrier and a toner.

A magnetic carrier comprising a magnetic carrier core and a resin coating layer formed on the surface of the magnetic carrier core, wherein the resin coating layer includes a polymer having a structure represented by the following formula (1), and a content ratio of the structure represented by the formula (1) is from 5% by mass to 95% by mass based on a resin component of the resin coating layer,

##STR00001## wherein, R.sup.1 is H or CH.sub.3, and X is a structure represented by the following formula (2):

(C.sub.mH.sub.2m)R.sup.2(C.sub.nH.sub.2n)OH (2) wherein, R.sup.2 is a hydrocarbon group being a cyclic structure having 4 to 8 carbon atoms, and m and n are integers of 0 to 4.

Provided is an electrostatic latent image developing toner including toner mother particles having an external additive on a surface of the toner mother particles, wherein the external additive contains inorganic particles and aliphatic acid metal salt particles; the inorganic particles have a number average particle diameter in the range of 10 to 50 nm, and have a Mohs hardness of 8 or more; and the aliphatic acid metal salt particles have a number average particle diameter in the range of 0.4 to 2.0 m.

An object of the present invention is to provide a ferrite particle having a low apparent density, filling a specified volume with a low weight with various properties maintained in a controllable state, a ferrite carrier core material composed of the ferrite particle, and a ferrite carrier using the ferrite core material and an electrophotographic developer. To achieve the object, the ferrite particle having the outer shell structure containing the Ti oxide for the ferrite carrier core material, and the ferrite carrier using the ferrite particle as the ferrite carrier core material and the electrophotographic developer are employed.

Provided are a magnetic core material for electrophotographic developer and a carrier for electrophotographic developer, which are excellent in charging characteristics and strength with low specific gravity and with which a satisfactory image free of defects can be obtained, and a developer containing the carrier.

A magnetic core material for electrophotographic developer, having a sulfur component content of from 60 to 800 ppm in terms of a sulfate ion and a pore volume of from 30 to 100 mm.sup.3/g.

A carrier core material is represented by a composition formula M.sub.XFe.sub.3-XO.sub.4 (where M is at least one type of metal element selected from Mg, Mn, Ca, Ti, Cu, Zn and Ni, 0<X<1), in which part of M and/or Fe is substituted with Sr and formed of ferrite particles, and in the carrier core material, a Sr content is equal to or more than 2500 ppm but equal to or less than 12000 ppm, the amount of Sr eluted with pure water at a temperature of 25 C. is equal to or less than 50 ppm, an apparent density is equal to or more than 1.85 g/cm.sup.3 but equal to or less than 2.25 g/cm.sup.3 and magnetization .sub.1k when a magnetic field of 79.5810.sup.3 A/m (1000 oersteds) is applied is equal to or more than 63 Am.sup.2/kg but equal to or less than 75 Am.sup.2/kg.

To provide a two-component developer for electrostatic charge image development, the two-component developer enabling a high image quality to be kept and enabling the occurrence of fogging to be suppressed even in continuous printing of an image high in coverage rate. The two-component developer for electrostatic charge image development includes a toner particle including a toner base particle and an external additive disposed on the surface of the toner base particle, and a carrier particle including a core material particle and a covering section disposed on the surface of the core material particle, wherein the external additive includes an alumina particle, and the percentage of exposed area of the core material particle is 4.0% or more and 15.0% or less.