INFORMATION RETRIEVING METHOD

PURPOSE:To shorten the retrieval time while obtaining a high hit rate at the time of retrieval as to the information retrieving means which retrieves information from a book data base for an information processing field by using a key word for retrieval. CONSTITUTION:When book data are registered, the book data to be registered are divided (101) into words by using a morpheme dictionary, a word which is not necessary as a key word is removed by using an unnecessary word dictionary to employ the result as the key word (102), and a high-order word for the key word is developed (103) by using a high-order word dictionary; and a synonym for the key word which is already generated is developed (104) by using a synonym dictionary, a compound word for the key word which is already generated is divided (105) by using a compound dictionary, and a synonym for the key word generated by dividing the compound word is developed (106) by using the synonym dictionary. Then a new key word is generated (107) by developing a different-notation word for the key word which is already generated by using a different-notation word dictionary.