An image forming system, having means for storing usage histories of latent image carriers, developer, or the like and maintenance cycles of image forming apparatuses and having a function for selecting image forming apparatuses outputting an image based on the usage history data or the maintenance cycles, in order to achieve uniform output image qualities. By managing the usage histories so as to achieve approximately the same deteriorated conditions of the latent image carriers of the image forming apparatuses, the image forming apparatuses can be put in the same condition and thus the output image qualities can be approximately the same in the image forming apparatuses. Additionally, the maintenance cycles can be adjusted to be approximately the same in the image forming apparatuses. Otherwise, maintenance periods can be controlled so as not to overlap in the image forming apparatuses.