Abstract: A developing device configured such that an amount of weakly charged toner in a two-component developer passing through an opening in the device per unit time is not greater than 200 g·mm/min, wherein the amount of weakly charged toner is expressed by an equation, which is the ? ? ? amount ? ? ? of ? ? ? weakly ? ? ? charged ? ? ? toner ? ? [ g · mm ? / ? min ] = total ? ? ? amount of ? ? ? the ? ? ? two ? - ? component ? ? ? developer ? ? ? to ? ? ? be ? ? ? drawn ? ? [ g ? / ? min ] × length of ? ? ? the ? ? ? opening ? ? [ mm ] × a ? ? ? concentration ? ? ? of ? ? ? toner ? ? [ wt ? ? ? % ] × percentage ? ? ? of ? ? ? weakly ? ? ? charged ? ? ? toner ? ? [ % ] .

Abstract: An image forming apparatus of the present invention includes a movable body to be charged and a charger including a charging member that contacts or adjoins the body to be charged and applies a voltage, including an AC component, to the charging member for thereby charging the body. A protection substance for protecting the surface of the body from deterioration ascribable to charging is caused to exist on the body. The number of particular elements, contained in the protection substance and detected by an X-ray photon spectral analyzer (XPS) in a zone where the charging member charges the body, is held in a particular ratio to the total number of all elements constituting the outermost surface of the body and also detected by the XPS.