Magnetic toner for developing electrostatic images

A magnetic toner obtained by mixing a binder resin and magnetic powder having a bulk density of 0.6 g/ml or larger in their powder states, thermally kneading the resultant mixture and pulverizing the kneaded product;

• said binder resin comprising substantially spherical particles having an average particle size of 0.1-0.7 mm or aggregates thereof;
• said binder resin having 10 to 70 wt. % of a THF (tetrahydrofuran)-insoluble and a THF-soluble, the THF-soluble providing a molecular weight distribution in the chromatogram of GPC (gel permeation chromatography) thereof such that it provides a rate (Mw/Mn) of weight-average molecular weight (Mw)/number-average molecular weight (Mn).gtoreq.5, there are at least one peak in the molecular weight range of 2,000 to 10,000 and at least one peak or shoulder in the molecular weight range of 15,000 to 100,000, and a component having a molecular weight of 10,000 or smaller is contained in an amount of 10-50 Wt. % based on the weight of the binder resin.