1. An information processing device comprising: an obtaining means that obtains a plurality of contents to which labels indicating users' subjective evaluation of the contents are assigned as metadata; a selection means that selects labels having a high reliability in regards to evaluation of the contents among the labels assigned to the plurality of contents obtained by the obtaining means; a calculation means that calculates a degree of similarity between the labels selected by the selection means; a clustering means that clusters the labels based on the degree of similarity calculated by the calculation means; and a storage means that stores a cluster obtained as a result of the clustering in the clustering means, as one label.