When a retrieval condition of an attribute list is input from a user interface unit to a retrieval processing unit, the attribute list stored in an attribute list storing unit is retrieved in the retrieval processing unit. Thereafter, attribute information conforming to the retrieval condition is output to and displayed on a displaying unit. Thereafter, when a retrieval condition of the similarity retrieval is input from the user interface unit to the retrieval processing unit, image data stored in the image information storing unit is retrieved in the retrieval processing unit, and specific image data relating to a characteristic descriptor set conforming to the retrieval condition is selected in the retrieval processing unit. Thereafter, the specific image data is output to and displayed on the displaying unit.