A method and apparatus for producing a keyword dictionary using a computer includes inputting a user's necessity or a user's non-necessity for each of pieces of information data, wherein one or more keywords are attached to the information data. A summed necessity value relating to the user's necessities inputted for the pieces of information data and a summed non-necessity value relating to the user's non-necessities inputted for the pieces of information data are calculated. A difference between the summed necessity value and the summed non-necessity value for each of the keywords is calculated, and a predication value predicting a user's necessity degree for each of the keywords according to the differences, respectively, relating to the keywords, is calculated. Each prediction value calculated is assigned to the corresponding keyword.