PURPOSE: To enable automatic detection when a phrase, that already temporarily becomes the object of replacement due to a synonym dictionary function is inputted again, namely, when a user inputs the phrase again, that is judged unpreferable by the user himself.

CONSTITUTION: A revised synonym dictionary function part 17 acquires an index phrase for retrieving a synonym dictionary data base 21 by using an input means 19. Sccessively, the synonym dictionary data base 21 is retrieved by a dictionary retrieving means 20 while using this index phrase and the list of replaced candidate phrases is prepared. Further, this list of replaced candidate phrases is provided to the user by a replacing means 22 and when the user selects any phrase, that phrase to be replaced is replaced with the phrase inputted by the input means 19. Afterwards, it is decided whether replacing work is executed or not and when that is not executed, the processing of the revised synonym dictionary function part 17 is finished.