An image forming apparatus includes an acquiring portion that acquires a duration of an overcharged state occurring in an area of an image bearing body charged by a charging member after the image bearing body is exposed by a preliminary exposing portion. Adjustment is made to an interval between a first timing when the preliminary exposing portion starts exposing the image bearing body before execution of an adjustment operation for setting a transfer voltage value and a second timing when a voltage applying portion starts, during the subsequent adjustment operation, applying a voltage with an adjustment voltage value to a transfer member such that the second timing is later than a third timing when the duration acquired by the acquiring portion ends.