An image forming device includes an image forming unit that includes a photoconductive drum which carries an electrostatic latent image, a developing roller which forms a developing nip by contacting the photoconductive drum and develops the latent image by using toner, and a transfer roller that forms a transferring nip by contacting the photoconductive drum and transfers a toner image onto a recording paper. A transferring voltage impressing circuit impresses to the transfer roller, a voltage of an opposite polarity to a polarity of a transfer process, for a prescribed period of time during a period when the recording paper is absent in the transferring nip. A developing voltage impressing circuit impresses to the developing roller, a voltage of a same polarity as a developing process and lower than the developing process when a field impressed with the voltage of the opposite polarity by the transferring voltage impressing circuit passes the developing nip.