A method of developing a latent image formed on an image carrier with toner, including causing a developer carrier, which faces the image carrier and accommodates a magnet therein, to support a developer having a toner and a magnetic carrier supporting the toner and convey the developer to a developing zone between the developer carrier and the image carrier, and providing an apparent coating ratio M of a surface of the developer carrier coated with the developer. The coating ration M is, in a zone upstream of the developing zone in a direction of rotation of the developer carrier, expressed as M=.alpha.A2+.beta. (%), where .alpha. denotes a coefficient of the coating ratio, A2 denotes an amount of developer for a unit area, .beta. denotes a value determined by a powder characteristic of the developer for an apparent coating ratio calculated with A2=0, and the coating ratio M is between 90% and 120%.