PURPOSE: To provide an extracting device which can extracts a more appropriate key word without depending upon surface expression by utilizing relation between words and a retrieval device which can perform a retrieve at a more appropriage retrieval request. CONSTITUTION: An expression extraction part 2 analyzes respective texts in document data inputted from a data input part 1 by a morpheme analysis part 14 to divide them into words, and then extracts plural mutually related words as expressions by a word group extraction part 15 on the basis of a word group extraction rule together with information on parts of speech. The expressions extracted by the expression extraction part 2 are related by a relation extraction part 3 on the basis of a relation extraction rule and further normalized by a normalization part 4. The related expressions normalized by the normalization part 4 are registered in a storage part 5 together with the inputted original data. The registered original data can be retrieved by using the related expression as a retrieval key.
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