1. A morphological analyzer for performing a morphological analysis on a natural language text to be processed, comprising: a dictionary unit storing header words and attribute information of the header words; a token list generating unit for referencing data in said dictionary unit, extracting tokens that can form the natural language text from said natural language text to be processed, and registering them on a token list; and a token string selecting unit for selecting optimum token strings for composing said natural language text on the basis of the token list generated by said token list generating unit, wherein said token list generating unit controls the registration of the tokens on said token list on the basis of conditions imposed on the morphological analysis and said attribute information of the header words corresponding to said extracted tokens.