1. An information processing device comprising a processor to implement: 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; a storage means that stores a cluster obtained as a result of the clustering in the clustering means, as one label; and a generation means that generates: a cluster discriminator which is a discriminator used to discriminate relevance to the cluster of the contents based on feature values of the contents assigned with the labels which are clustered by the clustering means; and a label discriminator which is a discriminator used to discriminate relevance to the clustered labels of the contents, wherein the storage means stores the cluster as one label when a discrimination accuracy of the cluster discriminator is better than a discrimination accuracy of the label discriminator, each feature value being associated with a plurality of classes, the plurality of classes being determined by analysis of physical properties for a plurality of the contents, and for each label, each feature value being set to one of the plurality of classes, and wherein the labels include labels in a plurality of respective languages, and the labels of different languages are clustered together based on the feature values such that a cluster includes labels of different languages.