Patent ID: 8718508

Claim:
An image forming apparatus comprising: an image bearing element having a surface on which a toner image is formed; an intermediate transfer element of which an outer peripheral surface moves along a predetermined revolving direction; a primary transfer element that primarily transfers the toner image from the surface of the image bearing element to the outer peripheral surface of the intermediate transfer element; a secondary transfer element that secondarily transfers the toner image from the intermediate transfer element to a sheet of paper; a pre-transfer charger that is located downstream of the primary transfer element and upstream of the secondary transfer element in the revolving direction, faces the outer peripheral surface of the intermediate transfer element along a perpendicular direction perpendicular to the revolving direction, and charges the intermediate transfer element when voltage is applied; and a control portion that, at a time when a determination process is performed as to necessity of cleaning the pre-transfer charger, secondarily transfers a cleaning assessment toner image by switching between a state in which the voltage is applied to the pre-transfer charger and a state in which the voltage is not applied to the pre-transfer charger, the cleaning assessment toner image having a uniform density within a range of a predetermined length along the revolving direction and within an entirety of an image forming region in the perpendicular direction.