1. An image forming apparatus comprising: a rotatable image bearing member; a charging device which charges the image bearing member; an electrostatic image forming device which forms an electrostatic image by exposing the image bearing member, the image bearing member being charged by the charging device; a development device which includes a developer bearing member to develop the electrostatic image in a form of a toner image, the developer bearing member bearing a developer containing toner and a magnetic carrier; and a controller capable of performing control such that a potential difference between a first non-image part on the image bearing member and the developer bearing member is smaller than a potential difference between a second non-image part on the image bearing member and the developer bearing member, the first non-image part being adjacent to an electrostatic image having a specific pattern on an upstream side in a rotating direction of the image bearing member.