1. An image carrier deterioration degree evaluating apparatus for evaluating a degree of deterioration of an image carrier of an image forming apparatus, the image carrier deterioration degree evaluating apparatus comprising: an image deletion detecting unit that detects image deletion by obtaining latent image information written on the image carrier; an image deletion reducing unit that performs a process of reducing image deletion when the image deletion detecting unit detects image deletion, and an image carrier deterioration degree evaluating unit that drives the image deletion detecting unit and the image deletion reducing unit alternately one or more times each, and evaluates a degree of deterioration of the image carrier by using the latent image information obtained one or more times by the image deletion detecting unit.