US Patent 8426094 Magnetic toner

A magnetic toner has magnetic toner particles, each of the magnetic toner particles containing a binder resin and a magnetic material, and an inorganic fine powder. The magnetic material is prepared by treating the surface of magnetic iron oxide with a silane compound. When the magnetic iron oxide is dispersed in an aqueous solution of hydrochloric acid and dissolved until the dissolution proportion of the iron element reaches 5% by mass based on the total amount of the iron element contained in the magnetic iron oxide, the amount of silicon eluted by that point of time is 0.05% by mass or more and 0.50% by mass or less based on the magnetic iron oxide. The magnetic material has a moisture adsorption amount per unit area of 0.30 mg/m2 or less.