1. An information categorizing apparatus comprising: a feature element extraction unit which extracts a feature element for each category, respectively, from a plurality of sample texts included in the categorizing sample information in which the plurality of sample texts and a plurality of categories are associated with each other in advance; a categorizing method determination unit which determines a categorizing method having the highest categorizing accuracy among a plurality of categorizing methods, based on the categorizing sample information; a categorizing learning information generation unit which generates categorizing learning information representing a feature for each category, based on the feature element extracted by said feature element extraction unit, in accordance with the categorizing method determined by said categorizing method determination unit; and a categorizing unit which categorizes a new text group to be categorized for each category, in accordance with the categorizing method determined by said categorizing method determination unit and the categorizing learning information.