Abstract: A developer for developing latent electrostatic images for use in the rear side exposure system, composed of an electroconductive magnetic carrier which is composed of electroconductive magnetic carrier particles, each electroconductive magnetic carrier particle including a magnetic base particle and an electroconductive layer formed on the surface of the magnetic base particle, a magnetic high-resistivity magnetic carrier, and an electrically insulating toner; and an image formation method of forming toner images on a photoconductor by using this developer in accordance with the rear side exposure system are disclosed.