IMAGE FORMING DEVICE

PURPOSE: To detect characteristic information of a photoreceptor drum, without providing a special member for setting the characteristic information by previously recording the characteristic information of the photoreceptor drum on its surface as the pattern of a toner image. CONSTITUTION: The sensitivity information (characteristic information) of the photoreceptor drum 10 obtained before a drum unit A is shipped is displayed as the pattern with a bar code, etc., by the toner image 10a on the end part side in the axial direction of the rotation of the drum 10. When it is decided that the drum unit A is new, the pattern by the toner image 10a is read by a wind detecting sensor 17. The read sensitivity information of the drum 10 is stored in a nonvolatile memory 18. When an error occurs at the time of reading the pattern display by the toner image 10a, the occurrence of the error is displayed in an error display part 19. The sensitivity information of the drum 10 is read out from the memory 18 and image forming conditions such as an exposure and a potential by electrification are set with the read sensitivity information.