FILE RETRIEVAL SYSTEM

PROBLEM TO BE SOLVED: To present proper information for narrowing-down to a user at the time of narrowing down plural files as the retrieval result to specific files. SOLUTION: When the user inputs a keyword for document data retrieval (step S21), retrieval of document data is started based on this keyword (step S22). When each acquired document data is registered in each storage area of a data base, a keyword is extracted from the document data, and its importance degree data and appearance rate data are calculated and are registered in the storage area (step S23). The degree of importance of each document data is calculated (step S24). The importance degree data and appearance rate data of each keyword and importance degree data of each document data are used to calculate data D indicating the degree of availability of document data narrowing-down with each keyword (step S27). K (or L%) keywords whose degrees of availability are higher are displayed as keywords for narrowing-down of document data (step S28), and their degrees of availability for each document data are displayed also (step S29).