PURPOSE: To stabilize a static charge characteristic of a magnetic toner and to enable forming a picture image of high quality even in the high humidity circumstances by mixing a magnetic carrier, a binder consisting of a styrene- acrylic copolymer having a specific acid value and a magnetic toner essentially consisting of magnetic powders subjected to a hydrophobization treatment.

CONSTITUTION: As the binder constituting the magnetic toner, the styrene-acrylic copolymer having <5 acid value and high esterification degree is used. As the magnetic powder constituting the magnetic toner, magnetic materials, such as metallic fine powders of iron, manganese, nickel, cobalt, chromium, etc., various kinds of ferrites, alloys or compounds of manganese, etc., and ferromagnetic alloy magnetite, are used. This constitution gives the moisture resistance to the binder and the magnetic powder essentially constituting the magnetic toner, thereby the static charge characteristic of the magnetic toner is stabilized and high quality image is formed even when the toner is used in the high humidity circumstances.