An image forming apparatus includes an image carrying member, a driving device, a charging member, a cleaning member, a voltage applying device, a torque detector for detecting the torque of the driving device, a storage for storing a predetermined torque value Tc, and a control portion. The control portion obtains as Ton the torque when the charging voltage is applied to the charging member and obtains as Toff the torque when no charging voltage is applied to the charging member. Let the torque observed when no charging voltage is applied at an early stage of use of the image carrying member be represented by Toff(0), then, when the relations Toff(0)