1. An image management system comprising: input means that inputs a first image; storage means that stores the first image; registration decision means that decides whether or not a second image with attendant information that is the same as attendant information of the first image is registered in the system; first registration means that registers the attendant information of the first image in association with the first image when the second image is not registered in the system; and second registration means that, when the second image is registered in the system and the attendant information of the second image is registered, registers information indicating that the first image is registered.