Dictionary creation device and dictionary creation method

In response to changes in the contents of the text information group, provides classify text information, search, or dictionary optimally created for extracting and updating the dictionary creation device and dictionary creation method capable of. Dictionary creation device (100), the keyword extraction section extracts the keyword from the text information input (1), keyword section to determine the statistics for the appearance of the keyword (2), based on the statistics for the appearance of the keyword extraction keyword evaluation value calculation unit for calculating an evaluation value of the keyword (3), determination unit configured to determine whether or not based on the calculated evaluation value whether or deleted to register this keyword (4), determination part (4) of dictionary registration deletion unit for registering or deleting keywords against dictionary database (102) by the results of the determination was performed (5), and the dictionary comprises a database (102).