To easily erase the previous image and form a fresh image on a paper sheet by excellently erasing a written part, except toner as well, without the futile consumption of a lot of toner at the time of forming the fresh image on the paper where the image has already been formed.

At the time of forming the fresh image on the paper 5 where the image has already been formed, the image forming method has a process for electrifying the surface of a photoreceptor 1, a reversal developing process for exposing the surface of the photoreceptor 1, based on the latest image information and imparting the toner whose color is different from that of the paper, to a photoreceptor part whose potential drops, a second developing process for exposing the surface of the photoreceptor 1, based on information of the image which has already been formed on the paper and imparting the toner having the same color as that of the paper, to a part whose potential does not drop and a transfer process for transferring each toner image formed on the surface of the photoreceptor 1 to the paper.