Image forming apparatus

An image forming apparatus having an image bearing member (1), a charger (2) to charge the surface of the image bearing member, an irradiator (3) to irradiate the image bearing member to form the latent image, a developing device (4) to develop the latent electrostatic image with toner to obtain a visible image, a transfer device (5) to transfer the visible image to a transfer medium by a transfer bias applied to a transfer area between the image bearing member and the transfer member, and a voltage detector (8) to measure a first surface voltage and a second surface voltage under different conditions, and a life status determination device (9) to identify whether or when the expected working life of the image bearing member has come to the end based on a comparison of the first surface voltage and the second surface voltage.