An inputting/designating section inputs a multimedia object or designates a multimedia object previously stored in a database. A feature-value-determining section determines the feature value of the input or designated multimedia object. A weighting-factor-determining section determines the determined feature-value weighting factor of the multimedia object. A similarity-retrieval section retrieves the similarity of the multimedia object previously stored in the database by using the determined feature value and the determined feature-value weighting factor. A displaying section displays a multimedia object similar to the multimedia object designated by the inputting/designating section in accordance with the result of similarity retrieval. A similarity-ranking-changing section changes similarity rankings of the displayed multimedia object. A similarity-recalculating section recalculates the feature-value weighting factor of the multimedia object in accordance with the changed similarity ranking and recalculates a similarity by using the feature-value weighting factor.