To provide an image forming device and process cartridge, which prevents an electrification irregularity in the form of a streak in a magnetic brush electrification process, resulting from an electrification irregularity in an auxiliary electrification process, also prevents an image defect in the form of a streak and a ghost image due to history of a previous image pattern, and obtains a satisfactory image.

An electrifying member is a magnetic brush, which is composed of magnetic particles 2-1 having an average particle diameter of 5 to 100 μm. An auxiliary electrifying member 6 is provided. The auxiliary electrifying member 6 is in contact with a photoreceptor while situated further upstream than the electrifying means and further downstream than a transfer means 4 in the direction of the movement of the photoreceptor 1. When a voltage having a polarity that is opposite to an electrifying polarity imparted by the electrifying means is applied to the auxiliary electrifying member 6, the member 6 electrifies the photoreceptor to the opposite polarity. The auxiliary electrifying member 6 is elastic, having a volume resistance of 1×104 to 1×109 Ω cm, a continuous surface that is in contact with the photoreceptor, and an average surface roughness Rz at ten points on the surface that is ≤15 μm.