PURPOSE: To enable formation of an image having high density and high resolution and good gradient characteristic without carrier carry-over by mixing two kinds of magnetic material particles having respectively different coercive forces and particle size distributions and prescribed resistance values thereby forming the carrier.

CONSTITUTION: A large-particle size carrier consisting of a magnetic material having ≥1013Ω.cm resistance value, high coercive force of ≥2,000e and 100W 500μm particle size distribution and a small particle size carrier consisting of an ordinary type of a magnetic material having ≤109Ω.cm resistance value, ≤5,000e coercive force and 10W100μm particle size distribution are mixed at a required ratio and the mixture composed thereof is used as a carrier, then the carrier for developing electrostatic latent images which can form the image having a good gradient characteristic with high density and high resolution without carrier carry-over is obtd.