To make the prevention of the lowering of the performance of a contact electrifying member compatible with the prolongation of the life of a body to be electrified in a tandem drum type image forming device.

This image forming device has a plurality of image forming units Y, M, C and K where an electrifying member 2 to which voltage is applied is made to abut on the body to be electrified 1 so as to electrify the body 1, the electrostatic latent image of image information is formed on the electrified surface of the body 1, and the electrostatic latent image formed on the body 1 is made visualizable as a toner image by a developing device, and the toner images formed by the respective image forming units Y, M, C and K are successively transferred to material to be transferred 6 so as to form an image. In a state where image forming processing is performed in at least one of the image forming units Y, M, C and K, the body to be electrified in the image forming unit for which the image forming processing is not performed is processed to be electrified.