A partial image identifying section extracts objects from an inputted image inputted by an image inputting section, and identifies types of the objects. A characteristic information generating section generates characteristic information of each object on the basis of a characteristic amount computed for each object. A plurality of partial image databases are provided for the respective types of objects. For each object, a degree of similarity computing section computes, on the basis of both characteristic information, degrees of similarity with all objects registered in the partial image database which corresponds to the type of the object. A photographing time period specifying section specifies a photographing time period, from the respective degrees of similarity computed by the degree of similarity computing section. A registering section registers extracted objects in association with the specified photographing time period, in the databases of the types corresponding to the objects.