1. An information processing device comprising: referring means for referring to a table in which a characteristic of each piece of first information is expressed as distribution of model parameters in a plurality of semantic classes, in units of pieces of the first information; obtaining means for obtaining second information to be searched for; calculating means for calculating similarities between the second information and the respective pieces of the first information; and first reading means for reading the pieces of the first information from the table in descending order of the similarity.