1. An information processing apparatus, comprising: an identification means for identifying categories to which contents belong among predetermined categories based on category metadata indicating the details of the contents and extracted content keyword information; and a clustering means for classifying a group of contents into clusters by performing clustering processing with respect to the group of contents belonging to the categories based on the metadata, wherein the clustering means supplies: the classified group of contents into clusters, names of the clusters, and information indicating attributes of the clusters, wherein the clustering means performs clustering processing by attaching importance to a standpoint of user's preference, and the information processing apparatus further comprising: a hierarchical structure changing means for changing hierarchical structure so that the clusters reflecting user's preference are arranged in a higher layer in the hierarchical structure including the categories and the clusters.