A carrier for developing an electrostatic charge image has magnetic particles and a resin coating that covers the magnetic particles and contains at least one lubricant. The resin coating has a dispersed phase of the lubricant and meets requirement (1). Requirement (1): the lubricant content in a top layer>the lubricant content in a middle layer>the lubricant content in a bottom layer The top, middle, and bottom layers are of the resin coating divided into three in the direction of thickness, and the lubricant content is the percentage area of the dispersed phase of the lubricant in a cross-section of the layer taken along the thickness thereof.

A carrier for developing an electrostatic charge image has magnetic particles and a resin coating that covers the magnetic particles and contains at least one lubricant. The resin coating has a dispersed phase of the lubricant and meets requirement (1). Requirement (1): the lubricant content in a top layer>the lubricant content in a middle layer>the lubricant content in a bottom layer The top, middle, and bottom layers are of the resin coating divided into three in the direction of thickness, and the lubricant content is the percentage area of the dispersed phase of the lubricant in a cross-section of the layer taken along the thickness thereof.

Provided are a ferrite carrier core material for an electrophotographic developer having a full length L.sub.1 of grain boundary and a circumference length L.sub.2 of the core material in a cross-section of the core material, and satisfying a relationship of 2≤L.sub.1/L.sub.2≤9; a carrier for an electrophotographic developer including the ferrite carrier core material and a coating layer containing a resin provided on a surface of the ferrite carrier core material; and an electrophotographic developer including the carrier and a toner.

Provided are a ferrite carrier core material for an electrophotographic developer having a full length L.sub.1 of grain boundary and a circumference length L.sub.2 of the core material in a cross-section of the core material, and satisfying a relationship of 2≤L.sub.1/L.sub.2≤9; a carrier for an electrophotographic developer including the ferrite carrier core material and a coating layer containing a resin provided on a surface of the ferrite carrier core material; and an electrophotographic developer including the carrier and a toner.

A two-component developer includes a toner including toner particles and a carrier including carrier particles. The toner particles each include a toner mother particle and an external additive attached to a surface of the toner mother particle. The external additive includes external additive particles. The external additive particles each include a base containing strontium titanate, a conductive layer covering the base, and a surface treatment layer either directly or indirectly covering the conductive layer. The surface treated layer contains a component derived from a hydrophobizing agent.

A two-component developer includes a toner including toner particles and a carrier including carrier particles. The toner particles each include a toner mother particle and an external additive attached to a surface of the toner mother particle. The external additive includes external additive particles. The external additive particles each include a base containing strontium titanate, a conductive layer covering the base, and a surface treatment layer either directly or indirectly covering the conductive layer. The surface treated layer contains a component derived from a hydrophobizing agent.

To provide a magnetic core material and carrier for electrophotographic developer, which have small environmental dependence of the electric resistance, can suppress the carrier scattering, and can stably provide good images; a developer contains the carrier; and methods for producing them. The magnetic core material satisfying a value of Formula (1): a+b×10+c+d+e+f, being from 20 to 150, when a fluoride ion amount is denoted by a (ppm), a chloride ion amount is denoted by b (ppm), a bromide ion amount is denoted by c (ppm), a nitrite ion amount is denoted by d (ppm), a nitrate ion amount is denoted by e (ppm), and a sulfate ion amount is denoted by f (ppm), which are measured by a combustion ion chromatography method.

An electrostatic charge image developer contains toner particles, layered-compound particles that are particles of a nitrogen-containing layered compound, and a resin-coated carrier that has magnetic particles and a resin layer covering the magnetic particles. The maximum height Ry of the roughness profile as defined in JIS B0601: 1994 of the surface of the resin-coated carrier is 0.01 μm or more and 0.20 μm or less.

An electrostatic image developer includes a toner containing toner particles, a carrier, and an external additive containing titanium dioxide particles of two types having different refractive indexes, fatty acid metal salt particles, and an abrasive.

According to one embodiment, a toner having excellent heat roller life performance, low-temperature offset resistance, and high-temperature offset resistance, and a toner cartridge and an image forming apparatus, in each of which the toner is stored, are provided.

A toner according to an embodiment contains a colorant, an amorphous polyester resin A, and an amorphous polyester resin B. The amorphous polyester resin A has an Mw.sub.A of 0.9×10.sup.4 to 1.5×10.sup.4. The amorphous polyester resin B has an Mw.sub.B of 4.0×10.sup.4 to 11.0×10.sup.4. The amorphous polyester resin A has an Mn.sub.A of 3.0×10.sup.3 to 4.0×10.sup.3. Mw.sub.A/Mn.sub.A is between 3.1 and 4.0. The amorphous polyester resin B has an Mn.sub.B of 2.2×10.sup.3 to 3.5×10.sup.3. Mw.sub.B/Mn.sub.B is between 11.4 and 50. The content of the amorphous polyester resin A is between 50 and 60 mass %. The content of the amorphous polyester resin B is between 20 and 30 mass %.