An apparatus is configured to charge an image bearing member in a charging section, develop an electrostatic image formed on the image bearing member, and transfer a toner image formed on the image bearing member to a transfer medium in a transfer section. The apparatus includes a charging auxiliary apparatus for changing a charge amount of toner on the image bearing member. The charging auxiliary apparatus includes a charging auxiliary member contacting with the image bearing member downstream of the transfer section and upstream of the charging section and a voltage applying device to apply a voltage to the charging auxiliary member. The apparatus includes a first detector to detect a current flowing in the charging auxiliary member during a period of non-image formation when the voltage is applied to the charging auxiliary member, a second detector to detect information regarding a toner density in the developing apparatus, and a control device to control toner supply to the developing apparatus based on detection results of both the detectors.