An image forming apparatus includes a photosensitive member, a charging device, a developing device, a thickness detecting unit and a parameter setting unit. A photosensitive layer is formed on a surface of the photosensitive member. The charging device charges the photosensitive member. The developing device forms a toner image on the surface of the photosensitive member. The thickness detecting unit detects a thickness of the photosensitive layer on a basis of a value of a current supplied to the charging device. When the thickness detecting unit detects the thickness of the photosensitive layer, the parameter setting unit sets at least one of a charge parameter for the charging device and a development parameter to be different from that used in forming an image on a recording medium by transferring a toner image formed on the surface of the photosensitive member onto the recording medium.