A method for developing electrostatic latent image on a rotating photoconductive drum by a magnetic developer transported by a rotating developing roll disposed opposite to the photoconductive drum, the developing roll being made of a cylindrical permanent magnet having on circumferential surface thereof equispaced magnetic poles extending along the axial direction. In the method the magnetic poles are equispaced by an inter-pole pitch of 0.5-10 mm, the photoconductive drum and the developing roll are rotated so as to move in opposite directions in an developing zone, and the ratio of peripheral speeds of the developing roll and photoconductive drum are regulated within 1 to 5. By the above method, an electrophotographic imaging apparatus can be reduced in the size thereof while reproducing high-quality images.