Provided is an image forming apparatus including a transfer mechanism which transfers a toner image formed on a photosensitive member onto a transfer receiving member, wherein the transfer mechanism includes a conductive member having resistance whose current-voltage characteristic changes by energization, and the image forming apparatus further includes a detector which detects a resistance value when currents or voltages of two or more levels are switched from one to another and applied to the conductive member, and a hardware processor which computes a slope of the current-voltage characteristic from the resistance value detected by the detector and determines a deterioration state of the conductive member by the slope.