PURPOSE: To obtain good two color images by using conductive carrier for the carrier of the first chromatic color developer and making the potentials after the development of the regions of the photoreceptor corresponding to the first chromatic color less than the development start voltage.

CONSTITUTION: Arrangement is so made that the residual potentials of the region a' corresponding to the first chromatic color, e.g., black, become less than the development start voltage V' after the first development. Because of this, conductive carrier is used for the carrier of the first chromatic color developer, i.e., black color developer, by which the latent image potential leakage from the carrier is increased at the first developing to reduce the residual potentials. As a result, at the time of the second development, the red toner of the second chromatic color deposits only on the region b' corresponding to red and does not depost in the region a' corresponding to black at the second developing. In this way, the good two color images may be obtained.