Patent ID: 7371494

Claim:
A magnetic toner comprising toner particles each containing at least a binder resin, a polar compound and a magnetic iron oxide fine particle, wherein: I) a ratio (B/A) of an iron element content (B) to a carbon element content (A) present on the surface of the toner particle, measured by X-ray photoelectron spectroscopy, is less than 0.0010; II) when a projected area diameter of toner particles obtained through cross-section observation of the toner particles using a transmission electron microscope (TEM) is denoted by C and a minimum value for a distance between a magnetic iron oxide fine particle and the toner particle surface is denoted by D, toner particles each satisfying a relationship of D/C≦0.02 are present in an amount of 50% by number or more; III) in the cross-section observation of the toner particles, toner particles, which satisfy a structure where 70% by number or more of the magnetic iron oxide fine particles in the respective toner particles are present up to a depth of 0.2 times as far as the projected area diameter C from the toner particle surface, are present in an amount of 40 to 95% by number; and IV) wherein the polar compound contains a maleic anhydride copolymer represented by following general formula (1) or a ring-opened compound of the maleic anhydride copolymer wherein A represents an alkylene group, R represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, n represents an integer of 1 to 20, x and y each represent a copolymerization ratio of each component, and x:y is from 10:90 to 90:10.