1 ) A translation system for translating a document, comprising: a dictionary management unit for managing a plurality of categorized dictionaries classified according to predetermined categories; a phrase extraction unit for extracting a noun phrase from said document; a registration category selection unit for selecting a category on which said extracted noun phrase should be registered among a plurality of categories corresponding to said plurality of categorized dictionaries, respectively; a translation unit for translating said noun phrase to generate a noun phrase translation which is a translation of said noun phrase; and a dictionary registration unit for registering a pair of said noun phrase and said noun phrase translation on said categorized dictionary corresponding to the category selected by said registration category selection unit.